Crex
Encyclopedia
Crex is a small genus
of bird
s in the rail family
. It contains two species, the Corn Crake
, C. crex, which breeds across Europe and Asia and winters in southern Africa, and the African Crake
, C. egregia, which migrates
within Africa. Both are short-billed rails with blackish-brown upperparts, mainly blue-grey underparts, and barring on the flanks. The Corn Crake is significantly larger than its relative, and has a distinctive chestnut
patch on its wings. Unusually for their family, these are birds of dry habitats rather than wetlands; the Eurasian species mainly breeds in hay meadows, and the African Crake in dry grassland. The African Crake is sometimes given its own genus, Crecopsis, but is now more usually placed in Crex.
Both species have distinctive loud grating calls used for advertising and territorial purposes in the breeding season, although the Corn Crake is silent on its African wintering grounds. They are mainly active during the day; they walk with a high-stepping action, and when disturbed they can run swiftly through grass or fly a short distance to cover. Migration takes place at night, and the ability to undertake these journeys is innate, not learned from adults. The nest is a shallow cup of grass lined with finer vegetation and built in a well hidden depression. The precocial
chicks leave the nest soon after hatching, and fledge
after four to six weeks. These are ground-feeding omnivore
s, but mainly eat invertebrate
s. They may be killed by a variety of mammals and large birds, and infected by parasites.
The two Crex species have huge breeding ranges and large populations and are classed as Least Concern
on the IUCN Red List
. The Corn Crake was formerly classified as Near Threatened
because of serious declines in western Europe, but improved monitoring shows that numbers have remained stable further east in Russia and Kazakhstan. In much of the western half of the Corn Crake's breeding range, there have been long-term declines that are expected to continue. The main cause of the decline is the loss of nests and chicks from early mowing. Haymaking dates have moved forward in the past century due to faster crop growth, made possible by land drainage and the use of fertilisers, and the move from manual grass-cutting using scythe
s to mechanical mower
s. Loss of habitat
is the other major threat to the Corn Crake. Drained and fertilised silage fields are less suitable for breeding than traditional hay meadows. In western Europe the conversion of grassland to arable land has been aided by subsidies, and further east the collapse of collective farming
has led to the abandonment and lack of management of much land in this important breeding area.
are a bird family
comprising nearly 150 species. Although the origins of the group are lost in antiquity, the largest number of species and the most primitive forms are found in the Old World
, suggesting that this family originated there. The genus Crex was created by German naturalist and ornithologist Johann Matthäus Bechstein
in 1803. Originally it held only the Corn Crake, C. crex, which Bechstein moved from its original name, Rallus crex, given to it by Linnaeus in his Systema Naturae
in 1758. The taxonomy of the small crakes is complicated, but the closest relative of the Corn Crake is the African Crake, C. egregia. This was first described as Ortygometra egregria by Wilhelm Peters
in 1854 from a specimen obtained in Mozambique, and has variously been placed in the genus Porzana
or its own genus, Crecopsis, but is now more usually placed in Crex. The Porzana
crakes are the closest relatives of the Crex genus, particularly the Ash-throated Crake
, Porzana albicollis, which has occasionally also been allocated to Crex.
The genus name is onomatopoeic, referring to the repetitive grating call of the Corn Crake. Although these species occur in fairly open habitats, they lack the pure white undertail used for signalling in open water or gregarious species like the coot
s and moorhen
s.
Both Crex crakes are short-billed birds with blackish-brown upperparts and mainly blue-grey underparts. The belly is white, and there is barring on the flanks and the underside of the short tail. The The Corn Crake is significantly larger than its relative, at 27–30 cm (10.6–11.8 in) long with a wingspan of 42–53 cm (16.5–20.9 in), compared to the African Crake's 20–23 cm (7.8–9.1 in) length and a 40–42 cm (15.7–16.5 in) wingspan. The Corn Crake is sympatric
with the African Crake on its wintering grounds, but can be distinguished by its larger size, paler upperparts, chestnut-coloured patch on the upperwing and different underparts pattern. In flight, it has longer, less rounded wings, and shallower wingbeats than its African relative, and shows a white leading edge to the inner wing.
The sexes of each species are similar in appearance, although the females are slightly smaller and duller than the males, with a less contrasting head pattern. Juveniles of both species are duller than the adults, and browner underneath. Adults undergo a complete moult after breeding. No subspecies
have been recognised of either Crex crake. Although Corn Crakes become paler and greyer towards the east of the range, the change is clinal, and there is great individual variation in colour within all populations.
The two Crex crakes are unlikely to be confused with other rails, since most sympatric short-billed rails are smaller, with white markings on the upperparts, different underparts patterns and shorter bills. The European Water Rail
and the African Rail
have long pointed bills.
The advertising calls of both crakes are readily distinguished from the quite dissimilar calls of potentially sympatric
rails such as the Spotted Crake
, Striped Crake
, Baillon's Crake
, or Water Rail
. The calls of the two Crex species cannot be confused, since the Corn Crake is silent in Africa. Both sexes may give distinctive territorial or alarm calls, and females and chicks communicate with cheeps and wheezes. The African Crake can be attracted to within 10 m (30 ft) of a human by imitation of its kraaa threat call, and the male Corn Crake by mechanical imitations of their advertising call, including rubbing a piece of wood down a notched stick, or by flicking a credit card against a comb or zip-fastener
.
east to central Siberia and western China. It winters in Africa from Zaire and central Tanzania south to eastern South Africa, mainly KwaZulu-Natal
and the former Transvaal Province
. Small numbers of birds may winter in the milder areas of western Europe, or halt their migration and stay in North Africa
.
The African Crake occurs throughout sub-Saharan Africa from Senegal east to Kenya and south to KwaZulu-Natal, except in arid areas of south and southwest Africa where the annual summer rainfall is less than 300 mm (11.8 in). It is widespread and locally common in most of its range, apart from the rainforest
s and the drier regions. Nearly all the South African population of about 8,000 birds occur in KwaZulu-Natal and the former Transvaal Province. This crake is only a vagrant
to the drier zones on the southern edges of South Africa's northern and eastern Cape Province
and North West Province
, and southern Botswana.
Both species are nocturnal migrants. Most Corn Crakes migrate through Egypt, with smaller numbers crossing at the western end of the Mediterranean
. It has been recorded in most countries between its breeding and wintering ranges, including much of west Africa, and those parts of southern Asia that lie between the east of the breeding range and Africa. Further afield, it has been recorded as a vagrant to Sri Lanka, Vietnam and Australia, the Seychelles, Bermuda, Canada, the United States, Greenland, and the North Atlantic islands.
The African species is a partial migrant
, but its movements are complex, seasonal and poorly studied. It is mainly a wet-season breeder, and many birds move away from the equator as soon as the rains provide sufficient grass cover to allow them to breed elsewhere. Southward movement is mainly from November to April, the return north beginning when burning or drought reduces the grass cover again. This species is present throughout the year in some West African countries, and in equatorial regions, but even in those areas numbers vary seasonally due to local movements; internal north–south migration has been noted within countries including Nigeria, Senegal, The Gambia, Ivory Coast and Cameroon. This crake has also wandered further afield. It is rare on Bioko Island
(Equatorial Guinea), and there have been two records each for São Tomé
and Tenerife
, the Canary Islands
birds being the first records for the Western Palaeartic.
Most rails are wetland
birds, but the two Crex species prefer drier habitats. The African Crake is found mainly in grassland, ranging from wetland edges and seasonal floodlands to savanna
, lightly wooded dry grassland, and grassy forest clearings. It also frequents maize, rice and cotton crops, derelict farmland and sugarcane plantations close to water. A wide range of grass species are used, with a preferred height of 0.3–1 m (1–3 ft) tall but vegetation is acceptable up to 2 m (6 ft) tall. The Corn Crake is mainly a lowland species, but breeds up to 1,400 m (4,600 ft) altitude in the Alps
, 2,700 m (8,600 ft) in China and 3,000 m (9,800 ft) in Russia. When breeding in Eurasia, the Corn Crake's habitats would originally have included river meadows with tall grass and meadow plants, but it is now mainly found in cool moist grassland used for the production of hay, particularly moist traditional farmland. It also utilises other treeless grasslands in mountains or taiga
, on coasts, or where created by fire. Very wet habitats are avoided, as are open areas and those with vegetation more than 50 cm (20 in) tall, or too dense for the birds to walk through.
While wintering in Africa, the Corn Crake occupies dry grassland and savanna habitats, occurring in vegetation 30–200 cm (1–6 ft) tall, including seasonally burnt areas and occasionally sedges or reed bed
s. It is also found on fallow and abandoned fields, uncut grass on airfields, and the edges of crops. It occurs at up to at least 1,750 m (5,700 ft) altitude in South Africa. Although it sometimes occurs with the African Crake, that species normally prefers moister and shorter grassland habitats than does the Corn Crake. On migration, the Corn Crake may also occur in wheatfields and around golf course
s.
Both species walk with a high-stepping action, and can run swiftly through grass with the body held horizontal and laterally flattened. When disturbed, they typically fly less than 50 m (150 ft), frequently landing behind a bush or thicket, and then go into a crouch. In short grass, they can escape from a dog using their speed and maneuverability, running with the body held almost horizontal. The typical flight is weak and fluttering, especially that of the African Crake, but for longer flights, such as migration, the Corn Crake has a steadier, stronger action with its legs drawn up. Flocks of up to 40 Corn Crakes may form on migration, sometimes associating with Common Quail
s. Migration takes place at night, and flocks resting during the day may aggregate to hundreds of birds at favoured sites. The ability to migrate is innate, not learned from adults; chicks raised from birds kept in captivity for ten generations were able to migrate to Africa and return with similar success to wild-bred young.
, but the male Corn Crake may have a shifting home range, and mate with two or more females, moving on when laying is almost complete. The breeding display consists of a short chase of the female by the male. The nest is a shallow cup of grass leaves and lined with finer grasses, built in a depression and well hidden in the grass. The clutch
size is from 3 to 11 pink eggs for the African species, and 6–14 – usually 8–12 – for the European breeder. The Corn Crake's eggs are oval, slightly glossy, creamy or tinted with green, blue or grey, and blotched red-brown. They average 37 × 26 mm, (1.5 × 1.0 in) and weigh about 13–16 g, (0.46–0.56 oz), of which 7% is shell.
The first egg is often laid when the nest is little more than a pad of grass, and a further egg is laid on each subsequent day. Both sexes incubate the eggs, which start hatching after about 14 days; all hatch with 48 hours despite the extended laying period. The black, downy precocial
chicks soon leave the nest but are fed and protected by the parents. Fledging
occurs after four to six weeks, and the young can fly before they are fully grown. It is not known whether the African Crake has a second brood, but the Corn Crake usually does. Where grass is not tall enough at the start of the season, the first nest may be constructed in herby or marsh vegetation, with the second brood in hay. The second nest may also be at a higher altitude that the first, to take advantage of the later-developing grasses further up a hill.
Although survival in undisturbed sites is high, at 80–90%, the Corn Crake suffers from modern farming practices, since mechanised mowing can kill 38–95% of chicks in a given site. The influence of weather on Corn Crake chick survival is limited: although chick growth is faster in dry or warm weather, the effects are relatively small. Unlike many precocial species, chicks are fed by their mother for a few days until they become independent, and this may cushion them from adverse conditions. The number of live chicks hatched is more important than the weather, with lower survival in large broods.
, but mainly feed on invertebrates, including earthworm
s, slug
s and snail
s, spider
s, beetle
s, dragonflies
, grasshopper
s and other insects. The Corn Crake may take pests such as Sitona
weevil
s, leatherjacket
s and wireworm
s. In Africa, termite
s, cockroach
es and dung beetle
s may be consumed. These opportunist hunters will take the occasional vertebrate
such as a small frog, rodent or fish. Food is taken from the ground, low-growing plants and from inside grass tussocks; the crake may search leaf litter with its bill, and run in pursuit of active prey. In Africa, both species will occasionally feed on grassy tracks or dirt roads. Plant material is eaten, especially grass seeds, but also green shoots, leaves and other seeds. As with other rails, grit is swallowed to help break up food in the stomach. Indigestible material is regurgitated as pellets
. Chicks are fed mainly on animal food. Crex crakes forage singly, in pairs or in family groups, sometimes in association with the other member of the genus or with other grassland birds such as Great Snipe
s, Blue Quail
s and Common Quails.
and domestic cat
s, introduced
American Mink
, feral Ferret
s, Otters
and Red Foxes
, and birds including the Common Buzzard
and Hooded Crow
. In Lithuania, the introduced Raccoon Dog
has also been recorded taking Corn Crakes. When chicks are exposed by rapid mowing, they may be taken by large birds including the White Stork
, harriers
and other birds of prey
, gull
s and corvids
. At undisturbed sites, nests and broods are rarely attacked, which is reflected in the high breeding success.
In Africa, Crex species may be hunted by the Leopard
, Serval
, cat
s, the Black-headed Heron
, Dark Chanting Goshawk
, African Hawk-Eagle, Wahlberg's Eagle
, and Black Sparrowhawk. In South Africa, newly hatched African Crake chicks were taken by a Boomslang
.
Parasites recorded in this genus include the widespread fluke
Prosthogonimus ovatus( which lives in the oviduct
s of birds), the parasitic worm
Plagiorchis elegans, the larvae of parasitic flies, the feather mite
Metanalges elongatus, and hard ticks
of the genera Haemaphysalis
and Ixodes
. During the reintroduction of Corn Crakes to England in the 2003 breeding season, enteritis
and ill heath in pre-release birds was due to bacteria
of a pathogen
ic Campylobacter
species. Subsequently, microbiology
tests were done to detect infected individuals and to find the source of the bacteria in their environment.
on the IUCN Red List
. The Corn Crake was formerly classified as Near Threatened
because of serious declines in Europe, but improved monitoring in Russia indicates that anticipated losses there have not occurred and numbers have remained stable or possibly increased in Russia and Kazakhstan. Although most rails in the Old World are covered by the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA), neither Crex species is listed, being too terrestrial to be classed as wetland species.
Overgrazing, agriculture and the loss of wetland and moist grassland have reduced the availability of suitable habitat for the African Crake in many areas, such as some parts of the southern KwaZulu-Natal coast which have been urbanised or planted with sugarcane. In other areas, grassland may have increased locally in recent years as woodland is cleared. This crake is considered to be good eating, and is killed for food in some regions. Despite these adverse factors, it appears to be under no real threat.
In much of the western half of the Corn Crake's breeding range, there have been long-term declines that are expected to continue, although conservation measures have enabled numbers to grow in several countries, including substantial increases in the small populations in Finland, the UK and the Netherlands. The breeding population had begun to decline in the 19th century, but the process gained pace after World War II. The main cause of the steep declines in much of Europe is the loss of nests and chicks from early mowing. Haymaking dates have moved forward in the past century due to faster crop growth, made possible by land drainage and the use of fertilisers, and the move from manual grass-cutting using scythes to mechanical mowers, at first horse-drawn and later pulled by tractors. Mechanisation also means that large areas can be cut quickly, leaving the crake with no alternative sites to raise either a first brood if suitable habitat has gone, or a replacement brood if the first nest is destroyed. The pattern of mowing, typically in a circular pattern from the outside of a field to its centre, gives little chance of escape for the chicks, which are also exposed to potential animal predators. Adults can often escape the mowers, although some incubating females sit tight on the nest, with fatal results.
Loss of habitat
is the other major threat to the Corn Crake, since drained and fertilised silage fields are less suitable for breeding than traditional hay meadows. In western Europe the conversion of grassland to arable land has been aided by subsidies, and further east the collapse of collective farming
has led to the abandonment and lack of management of much land in this important breeding area. More localised threats include floods in spring, and disturbance by roads or wind farm
s, and the loss of many birds – up to 14,000 a year – in Egypt, where migrating birds are captured in nets set for the quail with which they often migrate. Although this may account for 0.5–2.7% of the European population, the losses to this form of hunting are less than when the targeted species were more numerous and predictable.
Most European countries have taken steps to conserve the Corn Crake and produce national management policies; there is also an overall European action plan. The focus of conservation effort is to monitor populations and ecology
and to improve survival, principally through changing the timing and method of hay harvesting. Later cutting gives time for breeding to be completed, and leaving uncut strips at the edges of fields and cutting from the centre outwards reduces the casualties from mowing. Implementing these changes is predicted to stop the population decline if the measures are applied on a sufficiently large scale. Reduction of illegal hunting, and protection in countries where hunting is still allowed, are also conservation aims. Reintroduction of the Corn Crake is being attempted in England, and breeding sites are scheduled for protection in many other countries. Where breeding sites impinge on urban areas, there are cost implications, estimated in one German study at several million euros per Corn Crake. The Corn Crake does not appear to be seriously threatened on its wintering grounds and may benefit from deforestration, which creates more open habitats.
Crex is a small genus
of bird
s in the rail family
. It contains two species, the Corn Crake
, C. crex, which breeds across Europe and Asia and winters in southern Africa, and the African Crake
, C. egregia, which migrates
within Africa. Both are short-billed rails with blackish-brown upperparts, mainly blue-grey underparts, and barring on the flanks. The Corn Crake is significantly larger than its relative, and has a distinctive chestnut
patch on its wings. Unusually for their family, these are birds of dry habitats rather than wetlands; the Eurasian species mainly breeds in hay meadows, and the African Crake in dry grassland. The African Crake is sometimes given its own genus, Crecopsis, but is now more usually placed in Crex.
Both species have distinctive loud grating calls used for advertising and territorial purposes in the breeding season, although the Corn Crake is silent on its African wintering grounds. They are mainly active during the day; they walk with a high-stepping action, and when disturbed they can run swiftly through grass or fly a short distance to cover. Migration takes place at night, and the ability to undertake these journeys is innate, not learned from adults. The nest is a shallow cup of grass lined with finer vegetation and built in a well hidden depression. The precocial
chicks leave the nest soon after hatching, and fledge
after four to six weeks. These are ground-feeding omnivore
s, but mainly eat invertebrate
s. They may be killed by a variety of mammals and large birds, and infected by parasites.
The two Crex species have huge breeding ranges and large populations and are classed as Least Concern
on the IUCN Red List
. The Corn Crake was formerly classified as Near Threatened
because of serious declines in western Europe, but improved monitoring shows that numbers have remained stable further east in Russia and Kazakhstan. In much of the western half of the Corn Crake's breeding range, there have been long-term declines that are expected to continue. The main cause of the decline is the loss of nests and chicks from early mowing. Haymaking dates have moved forward in the past century due to faster crop growth, made possible by land drainage and the use of fertilisers, and the move from manual grass-cutting using scythe
s to mechanical mower
s. Loss of habitat
is the other major threat to the Corn Crake. Drained and fertilised silage fields are less suitable for breeding than traditional hay meadows. In western Europe the conversion of grassland to arable land has been aided by subsidies, and further east the collapse of collective farming
has led to the abandonment and lack of management of much land in this important breeding area.
are a bird family
comprising nearly 150 species. Although the origins of the group are lost in antiquity, the largest number of species and the most primitive forms are found in the Old World
, suggesting that this family originated there. The genus Crex was created by German naturalist and ornithologist Johann Matthäus Bechstein
in 1803. Originally it held only the Corn Crake, C. crex, which Bechstein moved from its original name, Rallus crex, given to it by Linnaeus in his Systema Naturae
in 1758. The taxonomy of the small crakes is complicated, but the closest relative of the Corn Crake is the African Crake, C. egregia. This was first described as Ortygometra egregria by Wilhelm Peters
in 1854 from a specimen obtained in Mozambique, and has variously been placed in the genus Porzana
or its own genus, Crecopsis, but is now more usually placed in Crex.Taylor & van Perlo (2000) p. 30Livezey (1998) p. 2098 The Porzana
crakes are the closest relatives of the Crex genus, particularly the Ash-throated Crake
, Porzana albicollis, which has occasionally also been allocated to Crex.Livezey (1998) p. 2134
The genus name is onomatopoeic, referring to the repetitive grating call of the Corn Crake. Although these species occur in fairly open habitats, they lack the pure white undertail used for signalling in open water or gregarious species like the coot
s and moorhen
s.
Both Crex crakes are short-billed birds with blackish-brown upperparts and mainly blue-grey underparts. The belly is white, and there is barring on the flanks and the underside of the short tail. The The Corn Crake is significantly larger than its relative, at 27–30 cm (10.6–11.8 in) long with a wingspan of 42–53 cm (16.5–20.9 in), compared to the African Crake's 20–23 cm (7.8–9.1 in) length and a 40–42 cm (15.7–16.5 in) wingspan. The Corn Crake is sympatric
with the African Crake on its wintering grounds, but can be distinguished by its larger size, paler upperparts, chestnut-coloured patch on the upperwing and different underparts pattern. In flight, it has longer, less rounded wings, and shallower wingbeats than its African relative, and shows a white leading edge to the inner wing.
The sexes of each species are similar in appearance, although the females are slightly smaller and duller than the males, with a less contrasting head pattern. Juveniles of both species are duller than the adults, and browner underneath. Adults undergo a complete moult after breeding. No subspecies
have been recognised of either Crex crake. Although Corn Crakes become paler and greyer towards the east of the range, the change is clinal, and there is great individual variation in colour within all populations.
The two Crex crakes are unlikely to be confused with other rails, since most sympatric short-billed rails are smaller, with white markings on the upperparts, different underparts patterns and shorter bills. The European Water Rail
and the African Rail
have long pointed bills.
The advertising calls of both crakes are readily distinguished from the quite dissimilar calls of potentially sympatric
rails such as the Spotted Crake
, Striped Crake
, Baillon's Crake
, or Water Rail
.Taylor & van Perlo (2000) pp. 293–299 The calls of the two Crex species cannot be confused, since the Corn Crake is silent in Africa. Both sexes may give distinctive territorial or alarm calls, and females and chicks communicate with cheeps and wheezes. The African Crake can be attracted to within 10 m (30 ft) of a human by imitation of its kraaa threat call, and the male Corn Crake by mechanical imitations of their advertising call, including rubbing a piece of wood down a notched stick, or by flicking a credit card against a comb or zip-fastener
.
east to central Siberia and western China. It winters in Africa from Zaire and central Tanzania south to eastern South Africa, mainly KwaZulu-Natal
and the former Transvaal Province
. Small numbers of birds may winter in the milder areas of western Europe, or halt their migration and stay in North Africa
.
The African Crake occurs throughout sub-Saharan Africa from Senegal east to Kenya and south to KwaZulu-Natal, except in arid areas of south and southwest Africa where the annual summer rainfall is less than 300 mm (11.8 in). It is widespread and locally common in most of its range, apart from the rainforest
s and the drier regions. Nearly all the South African population of about 8,000 birds occur in KwaZulu-Natal and the former Transvaal Province. This crake is only a vagrant
to the drier zones on the southern edges of South Africa's northern and eastern Cape Province
and North West Province
, and southern Botswana. Retrieved 26 May 2011
Both species are nocturnal migrants. Most Corn Crakes migrate through Egypt, with smaller numbers crossing at the western end of the Mediterranean
. It has been recorded in most countries between its breeding and wintering ranges, including much of west Africa, and those parts of southern Asia that lie between the east of the breeding range and Africa. Further afield, it has been recorded as a vagrant to Sri Lanka, Vietnam and Australia,Bräunlich, Axel; Rank, Michael (2001)Notes on the occurrence of the Corncrake (Crex crex) in Asia and in the Pacific region pp. 10–13 in Schäffer, N; Mammen, U (eds.) (2001) Proceedings International Corncrake Workshop 1998, Hilpoltstein/Germany. the Seychelles, Bermuda, Canada, the United States, Greenland, and the North Atlantic islands.
The African species is a partial migrant
, but its movements are complex, seasonal and poorly studied. It is mainly a wet-season breeder, and many birds move away from the equator as soon as the rains provide sufficient grass cover to allow them to breed elsewhere. Southward movement is mainly from November to April, the return north beginning when burning or drought reduces the grass cover again. This species is present throughout the year in some West African countries, and in equatorial regions, but even in those areas numbers vary seasonally due to local movements; internal north–south migration has been noted within countries including Nigeria, Senegal, The Gambia, Ivory Coast and Cameroon. This crake has also wandered further afield. It is rare on Bioko Island
(Equatorial Guinea),Larison, Brenda; Smith, Thomas B; Milá, Borja; Stauffer, Donald; Nguema, José (1999) " Bird and Mammal Surveys of Rio Muni" pp. 9–57 in and there have been two records each for São Tomé
and Tenerife
, the Canary Islands
birds being the first records for the Western Palaeartic.
Most rails are wetland
birds, but the two Crex species prefer drier habitats. The African Crake is found mainly in grassland, ranging from wetland edges and seasonal floodlands to savanna
, lightly wooded dry grassland, and grassy forest clearings. It also frequents maize, rice and cotton crops, derelict farmland and sugarcane plantations close to water. A wide range of grass species are used, with a preferred height of 0.3–1 m (1–3 ft) tall but vegetation is acceptable up to 2 m (6 ft) tall. The Corn Crake is mainly a lowland species, but breeds up to 1,400 m (4,600 ft) altitude in the Alps
, 2,700 m (8,600 ft) in China and 3,000 m (9,800 ft) in Russia. When breeding in Eurasia, the Corn Crake's habitats would originally have included river meadows with tall grass and meadow plants, but it is now mainly found in cool moist grassland used for the production of hay, particularly moist traditional farmland. It also utilises other treeless grasslands in mountains or taiga
, on coasts, or where created by fire. Very wet habitats are avoided, as are open areas and those with vegetation more than 50 cm (20 in) tall, or too dense for the birds to walk through.
While wintering in Africa, the Corn Crake occupies dry grassland and savanna habitats, occurring in vegetation 30–200 cm (1–6 ft) tall, including seasonally burnt areas and occasionally sedges or reed bed
s. It is also found on fallow and abandoned fields, uncut grass on airfields, and the edges of crops. It occurs at up to at least 1,750 m (5,700 ft) altitude in South Africa. Although it sometimes occurs with the African Crake, that species normally prefers moister and shorter grassland habitats than does the Corn Crake. On migration, the Corn Crake may also occur in wheatfields and around golf course
s.
Both species walk with a high-stepping action, and can run swiftly through grass with the body held horizontal and laterally flattened. When disturbed, they typically fly less than 50 m (150 ft), frequently landing behind a bush or thicket, and then go into a crouch. In short grass, they can escape from a dog using their speed and maneuverability, running with the body held almost horizontal. The typical flight is weak and fluttering, especially that of the African Crake, but for longer flights, such as migration, the Corn Crake has a steadier, stronger action with its legs drawn up. Flocks of up to 40 Corn Crakes may form on migration, sometimes associating with Common Quail
s. Migration takes place at night, and flocks resting during the day may aggregate to hundreds of birds at favoured sites. The ability to migrate is innate, not learned from adults; chicks raised from birds kept in captivity for ten generations were able to migrate to Africa and return with similar success to wild-bred young.
, but the male Corn Crake may have a shifting home range, and mate with two or more females, moving on when laying is almost complete. The breeding display consists of a short chase of the female by the male. The nest is a shallow cup of grass leaves and lined with finer grasses, built in a depression and well hidden in the grass. The clutch
size is from 3 to 11 pink eggs for the African species, and 6–14 – usually 8–12 – for the European breeder. The Corn Crake's eggs are oval, slightly glossy, creamy or tinted with green, blue or grey, and blotched red-brown. They average 37 × 26 mm, (1.5 × 1.0 in) and weigh about 13–16 g, (0.46–0.56 oz), of which 7% is shell.
The first egg is often laid when the nest is little more than a pad of grass, and a further egg is laid on each subsequent day. Both sexes incubate the eggs, which start hatching after about 14 days; all hatch with 48 hours despite the extended laying period. The black, downy precocial
chicks soon leave the nest but are fed and protected by the parents. Fledging
occurs after four to six weeks, and the young can fly before they are fully grown. It is not known whether the African Crake has a second brood, but the Corn Crake usually does. Where grass is not tall enough at the start of the season, the first nest may be constructed in herby or marsh vegetation, with the second brood in hay. The second nest may also be at a higher altitude that the first, to take advantage of the later-developing grasses further up a hill.
Although survival in undisturbed sites is high, at 80–90%, the Corn Crake suffers from modern farming practices, since mechanised mowing can kill 38–95% of chicks in a given site. The influence of weather on Corn Crake chick survival is limited: although chick growth is faster in dry or warm weather, the effects are relatively small. Unlike many precocial species, chicks are fed by their mother for a few days until they become independent, and this may cushion them from adverse conditions. The number of live chicks hatched is more important than the weather, with lower survival in large broods.
, but mainly feed on invertebrates, including earthworm
s, slug
s and snail
s, spider
s, beetle
s, dragonflies
, grasshopper
s and other insects. The Corn Crake may take pests such as Sitona
weevil
s, leatherjacket
s and wireworm
s. In Africa, termite
s, cockroach
es and dung beetle
s may be consumed. These opportunist hunters will take the occasional vertebrate
such as a small frog, rodent or fish. Food is taken from the ground, low-growing plants and from inside grass tussocks; the crake may search leaf litter with its bill, and run in pursuit of active prey. In Africa, both species will occasionally feed on grassy tracks or dirt roads. Plant material is eaten, especially grass seeds, but also green shoots, leaves and other seeds. As with other rails, grit is swallowed to help break up food in the stomach. Indigestible material is regurgitated as pellets
. Chicks are fed mainly on animal food. Crex crakes forage singly, in pairs or in family groups, sometimes in association with the other member of the genus or with other grassland birds such as Great Snipe
s, Blue Quail
s and Common Quails.
and domestic cat
s, introduced
American Mink
, feral Ferret
s, Otters
and Red Foxes
, and birds including the Common Buzzard
and Hooded Crow
. In Lithuania, the introduced Raccoon Dog
has also been recorded taking Corn Crakes. When chicks are exposed by rapid mowing, they may be taken by large birds including the White Stork
, harriers
and other birds of prey
, gull
s and corvids
.Koffijberg & Schaffer (2006) p. 21 At undisturbed sites, nests and broods are rarely attacked, which is reflected in the high breeding success.
In Africa, Crex species may be hunted by the Leopard
, Serval
, cat
s, the Black-headed Heron
, Dark Chanting Goshawk
, African Hawk-Eagle, Wahlberg's Eagle
,Taylor & van Perlo (2000) pp. 316–320 and Black Sparrowhawk.Taylor & van Perlo (2000) pp. 320–327 In South Africa, newly hatched African Crake chicks were taken by a Boomslang
.
Parasites recorded in this genus include the widespread fluke
Prosthogonimus ovatus( which lives in the oviduct
s of birds), the parasitic worm
Plagiorchis elegans, the larvae of parasitic flies, the feather mite
Metanalges elongatus, and hard ticks
of the genera Haemaphysalis
and Ixodes
. During the reintroduction of Corn Crakes to England in the 2003 breeding season, enteritis
and ill heath in pre-release birds was due to bacteria
of a pathogen
ic Campylobacter
species. Subsequently, microbiology
tests were done to detect infected individuals and to find the source of the bacteria in their environment.
on the IUCN Red List
. The Corn Crake was formerly classified as Near Threatened
because of serious declines in Europe, but improved monitoring in Russia indicates that anticipated losses there have not occurred and numbers have remained stable or possibly increased in Russia and Kazakhstan. Although most rails in the Old World are covered by the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA), neither Crex species is listed, being too terrestrial to be classed as wetland species.
Overgrazing, agriculture and the loss of wetland and moist grassland have reduced the availability of suitable habitat for the African Crake in many areas, such as some parts of the southern KwaZulu-Natal coast which have been urbanised or planted with sugarcane. In other areas, grassland may have increased locally in recent years as woodland is cleared. This crake is considered to be good eating, and is killed for food in some regions. Despite these adverse factors, it appears to be under no real threat.
In much of the western half of the Corn Crake's breeding range, there have been long-term declines that are expected to continue, although conservation measures have enabled numbers to grow in several countries, including substantial increases in the small populations in Finland, the UK and the Netherlands. The breeding population had begun to decline in the 19th century, but the process gained pace after World War II.Koffijberg & Schaffer (2006) p. 6 The main cause of the steep declines in much of Europe is the loss of nests and chicks from early mowing. Haymaking dates have moved forward in the past century due to faster crop growth, made possible by land drainage and the use of fertilisers, and the move from manual grass-cutting using scythes to mechanical mowers, at first horse-drawn and later pulled by tractors. Mechanisation also means that large areas can be cut quickly, leaving the crake with no alternative sites to raise either a first brood if suitable habitat has gone, or a replacement brood if the first nest is destroyed. The pattern of mowing, typically in a circular pattern from the outside of a field to its centre, gives little chance of escape for the chicks, which are also exposed to potential animal predators. Adults can often escape the mowers, although some incubating females sit tight on the nest, with fatal results.
Loss of habitat
is the other major threat to the Corn Crake, since drained and fertilised silage fields are less suitable for breeding than traditional hay meadows. In western Europe the conversion of grassland to arable land has been aided by subsidies, and further east the collapse of collective farming
has led to the abandonment and lack of management of much land in this important breeding area. More localised threats include floods in spring, and disturbance by roads or wind farm
s, and the loss of many birds – up to 14,000 a year – in Egypt, where migrating birds are captured in nets set for the quail with which they often migrate. Although this may account for 0.5–2.7% of the European population, the losses to this form of hunting are less than when the targeted species were more numerous and predictable.
Most European countries have taken steps to conserve the Corn Crake and produce national management policies; there is also an overall European action plan. The focus of conservation effort is to monitor populations and ecology
and to improve survival, principally through changing the timing and method of hay harvesting. Later cutting gives time for breeding to be completed, and leaving uncut strips at the edges of fields and cutting from the centre outwards reduces the casualties from mowing. Implementing these changes is predicted to stop the population decline if the measures are applied on a sufficiently large scale. Reduction of illegal hunting, and protection in countries where hunting is still allowed, are also conservation aims. Reintroduction of the Corn Crake is being attempted in England, and breeding sites are scheduled for protection in many other countries. Where breeding sites impinge on urban areas, there are cost implications, estimated in one German study at several million euros per Corn Crake. The Corn Crake does not appear to be seriously threatened on its wintering grounds and may benefit from deforestration, which creates more open habitats.
Crex is a small genus
of bird
s in the rail family
. It contains two species, the Corn Crake
, C. crex, which breeds across Europe and Asia and winters in southern Africa, and the African Crake
, C. egregia, which migrates
within Africa. Both are short-billed rails with blackish-brown upperparts, mainly blue-grey underparts, and barring on the flanks. The Corn Crake is significantly larger than its relative, and has a distinctive chestnut
patch on its wings. Unusually for their family, these are birds of dry habitats rather than wetlands; the Eurasian species mainly breeds in hay meadows, and the African Crake in dry grassland. The African Crake is sometimes given its own genus, Crecopsis, but is now more usually placed in Crex.
Both species have distinctive loud grating calls used for advertising and territorial purposes in the breeding season, although the Corn Crake is silent on its African wintering grounds. They are mainly active during the day; they walk with a high-stepping action, and when disturbed they can run swiftly through grass or fly a short distance to cover. Migration takes place at night, and the ability to undertake these journeys is innate, not learned from adults. The nest is a shallow cup of grass lined with finer vegetation and built in a well hidden depression. The precocial
chicks leave the nest soon after hatching, and fledge
after four to six weeks. These are ground-feeding omnivore
s, but mainly eat invertebrate
s. They may be killed by a variety of mammals and large birds, and infected by parasites.
The two Crex species have huge breeding ranges and large populations and are classed as Least Concern
on the IUCN Red List
. The Corn Crake was formerly classified as Near Threatened
because of serious declines in western Europe, but improved monitoring shows that numbers have remained stable further east in Russia and Kazakhstan. In much of the western half of the Corn Crake's breeding range, there have been long-term declines that are expected to continue. The main cause of the decline is the loss of nests and chicks from early mowing. Haymaking dates have moved forward in the past century due to faster crop growth, made possible by land drainage and the use of fertilisers, and the move from manual grass-cutting using scythe
s to mechanical mower
s. Loss of habitat
is the other major threat to the Corn Crake. Drained and fertilised silage fields are less suitable for breeding than traditional hay meadows. In western Europe the conversion of grassland to arable land has been aided by subsidies, and further east the collapse of collective farming
has led to the abandonment and lack of management of much land in this important breeding area.
are a bird family
comprising nearly 150 species. Although the origins of the group are lost in antiquity, the largest number of species and the most primitive forms are found in the Old World
, suggesting that this family originated there. The genus Crex was created by German naturalist and ornithologist Johann Matthäus Bechstein
in 1803. Originally it held only the Corn Crake, C. crex, which Bechstein moved from its original name, Rallus crex, given to it by Linnaeus in his Systema Naturae
in 1758. The taxonomy of the small crakes is complicated, but the closest relative of the Corn Crake is the African Crake, C. egregia. This was first described as Ortygometra egregria by Wilhelm Peters
in 1854 from a specimen obtained in Mozambique, and has variously been placed in the genus Porzana
or its own genus, Crecopsis, but is now more usually placed in Crex.Taylor & van Perlo (2000) p. 30Livezey (1998) p. 2098 The Porzana
crakes are the closest relatives of the Crex genus, particularly the Ash-throated Crake
, Porzana albicollis, which has occasionally also been allocated to Crex.Livezey (1998) p. 2134
The genus name is onomatopoeic, referring to the repetitive grating call of the Corn Crake. Although these species occur in fairly open habitats, they lack the pure white undertail used for signalling in open water or gregarious species like the coot
s and moorhen
s.
Both Crex crakes are short-billed birds with blackish-brown upperparts and mainly blue-grey underparts. The belly is white, and there is barring on the flanks and the underside of the short tail. The The Corn Crake is significantly larger than its relative, at 27–30 cm (10.6–11.8 in) long with a wingspan of 42–53 cm (16.5–20.9 in), compared to the African Crake's 20–23 cm (7.8–9.1 in) length and a 40–42 cm (15.7–16.5 in) wingspan. The Corn Crake is sympatric
with the African Crake on its wintering grounds, but can be distinguished by its larger size, paler upperparts, chestnut-coloured patch on the upperwing and different underparts pattern. In flight, it has longer, less rounded wings, and shallower wingbeats than its African relative, and shows a white leading edge to the inner wing.
The sexes of each species are similar in appearance, although the females are slightly smaller and duller than the males, with a less contrasting head pattern. Juveniles of both species are duller than the adults, and browner underneath. Adults undergo a complete moult after breeding. No subspecies
have been recognised of either Crex crake. Although Corn Crakes become paler and greyer towards the east of the range, the change is clinal, and there is great individual variation in colour within all populations.
The two Crex crakes are unlikely to be confused with other rails, since most sympatric short-billed rails are smaller, with white markings on the upperparts, different underparts patterns and shorter bills. The European Water Rail
and the African Rail
have long pointed bills.
The advertising calls of both crakes are readily distinguished from the quite dissimilar calls of potentially sympatric
rails such as the Spotted Crake
, Striped Crake
, Baillon's Crake
, or Water Rail
.Taylor & van Perlo (2000) pp. 293–299 The calls of the two Crex species cannot be confused, since the Corn Crake is silent in Africa. Both sexes may give distinctive territorial or alarm calls, and females and chicks communicate with cheeps and wheezes. The African Crake can be attracted to within 10 m (30 ft) of a human by imitation of its kraaa threat call, and the male Corn Crake by mechanical imitations of their advertising call, including rubbing a piece of wood down a notched stick, or by flicking a credit card against a comb or zip-fastener
.
east to central Siberia and western China. It winters in Africa from Zaire and central Tanzania south to eastern South Africa, mainly KwaZulu-Natal
and the former Transvaal Province
. Small numbers of birds may winter in the milder areas of western Europe, or halt their migration and stay in North Africa
.
The African Crake occurs throughout sub-Saharan Africa from Senegal east to Kenya and south to KwaZulu-Natal, except in arid areas of south and southwest Africa where the annual summer rainfall is less than 300 mm (11.8 in). It is widespread and locally common in most of its range, apart from the rainforest
s and the drier regions. Nearly all the South African population of about 8,000 birds occur in KwaZulu-Natal and the former Transvaal Province. This crake is only a vagrant
to the drier zones on the southern edges of South Africa's northern and eastern Cape Province
and North West Province
, and southern Botswana. Retrieved 26 May 2011
Both species are nocturnal migrants. Most Corn Crakes migrate through Egypt, with smaller numbers crossing at the western end of the Mediterranean
. It has been recorded in most countries between its breeding and wintering ranges, including much of west Africa, and those parts of southern Asia that lie between the east of the breeding range and Africa. Further afield, it has been recorded as a vagrant to Sri Lanka, Vietnam and Australia,Bräunlich, Axel; Rank, Michael (2001)Notes on the occurrence of the Corncrake (Crex crex) in Asia and in the Pacific region pp. 10–13 in Schäffer, N; Mammen, U (eds.) (2001) Proceedings International Corncrake Workshop 1998, Hilpoltstein/Germany. the Seychelles, Bermuda, Canada, the United States, Greenland, and the North Atlantic islands.
The African species is a partial migrant
, but its movements are complex, seasonal and poorly studied. It is mainly a wet-season breeder, and many birds move away from the equator as soon as the rains provide sufficient grass cover to allow them to breed elsewhere. Southward movement is mainly from November to April, the return north beginning when burning or drought reduces the grass cover again. This species is present throughout the year in some West African countries, and in equatorial regions, but even in those areas numbers vary seasonally due to local movements; internal north–south migration has been noted within countries including Nigeria, Senegal, The Gambia, Ivory Coast and Cameroon. This crake has also wandered further afield. It is rare on Bioko Island
(Equatorial Guinea),Larison, Brenda; Smith, Thomas B; Milá, Borja; Stauffer, Donald; Nguema, José (1999) " Bird and Mammal Surveys of Rio Muni" pp. 9–57 in and there have been two records each for São Tomé
and Tenerife
, the Canary Islands
birds being the first records for the Western Palaeartic.
Most rails are wetland
birds, but the two Crex species prefer drier habitats. The African Crake is found mainly in grassland, ranging from wetland edges and seasonal floodlands to savanna
, lightly wooded dry grassland, and grassy forest clearings. It also frequents maize, rice and cotton crops, derelict farmland and sugarcane plantations close to water. A wide range of grass species are used, with a preferred height of 0.3–1 m (1–3 ft) tall but vegetation is acceptable up to 2 m (6 ft) tall. The Corn Crake is mainly a lowland species, but breeds up to 1,400 m (4,600 ft) altitude in the Alps
, 2,700 m (8,600 ft) in China and 3,000 m (9,800 ft) in Russia. When breeding in Eurasia, the Corn Crake's habitats would originally have included river meadows with tall grass and meadow plants, but it is now mainly found in cool moist grassland used for the production of hay, particularly moist traditional farmland. It also utilises other treeless grasslands in mountains or taiga
, on coasts, or where created by fire. Very wet habitats are avoided, as are open areas and those with vegetation more than 50 cm (20 in) tall, or too dense for the birds to walk through.
While wintering in Africa, the Corn Crake occupies dry grassland and savanna habitats, occurring in vegetation 30–200 cm (1–6 ft) tall, including seasonally burnt areas and occasionally sedges or reed bed
s. It is also found on fallow and abandoned fields, uncut grass on airfields, and the edges of crops. It occurs at up to at least 1,750 m (5,700 ft) altitude in South Africa. Although it sometimes occurs with the African Crake, that species normally prefers moister and shorter grassland habitats than does the Corn Crake. On migration, the Corn Crake may also occur in wheatfields and around golf course
s.
Both species walk with a high-stepping action, and can run swiftly through grass with the body held horizontal and laterally flattened. When disturbed, they typically fly less than 50 m (150 ft), frequently landing behind a bush or thicket, and then go into a crouch. In short grass, they can escape from a dog using their speed and maneuverability, running with the body held almost horizontal. The typical flight is weak and fluttering, especially that of the African Crake, but for longer flights, such as migration, the Corn Crake has a steadier, stronger action with its legs drawn up. Flocks of up to 40 Corn Crakes may form on migration, sometimes associating with Common Quail
s. Migration takes place at night, and flocks resting during the day may aggregate to hundreds of birds at favoured sites. The ability to migrate is innate, not learned from adults; chicks raised from birds kept in captivity for ten generations were able to migrate to Africa and return with similar success to wild-bred young.
, but the male Corn Crake may have a shifting home range, and mate with two or more females, moving on when laying is almost complete. The breeding display consists of a short chase of the female by the male. The nest is a shallow cup of grass leaves and lined with finer grasses, built in a depression and well hidden in the grass. The clutch
size is from 3 to 11 pink eggs for the African species, and 6–14 – usually 8–12 – for the European breeder. The Corn Crake's eggs are oval, slightly glossy, creamy or tinted with green, blue or grey, and blotched red-brown. They average 37 × 26 mm, (1.5 × 1.0 in) and weigh about 13–16 g, (0.46–0.56 oz), of which 7% is shell.
The first egg is often laid when the nest is little more than a pad of grass, and a further egg is laid on each subsequent day. Both sexes incubate the eggs, which start hatching after about 14 days; all hatch with 48 hours despite the extended laying period. The black, downy precocial
chicks soon leave the nest but are fed and protected by the parents. Fledging
occurs after four to six weeks, and the young can fly before they are fully grown. It is not known whether the African Crake has a second brood, but the Corn Crake usually does. Where grass is not tall enough at the start of the season, the first nest may be constructed in herby or marsh vegetation, with the second brood in hay. The second nest may also be at a higher altitude that the first, to take advantage of the later-developing grasses further up a hill.
Although survival in undisturbed sites is high, at 80–90%, the Corn Crake suffers from modern farming practices, since mechanised mowing can kill 38–95% of chicks in a given site. The influence of weather on Corn Crake chick survival is limited: although chick growth is faster in dry or warm weather, the effects are relatively small. Unlike many precocial species, chicks are fed by their mother for a few days until they become independent, and this may cushion them from adverse conditions. The number of live chicks hatched is more important than the weather, with lower survival in large broods.
, but mainly feed on invertebrates, including earthworm
s, slug
s and snail
s, spider
s, beetle
s, dragonflies
, grasshopper
s and other insects. The Corn Crake may take pests such as Sitona
weevil
s, leatherjacket
s and wireworm
s. In Africa, termite
s, cockroach
es and dung beetle
s may be consumed. These opportunist hunters will take the occasional vertebrate
such as a small frog, rodent or fish. Food is taken from the ground, low-growing plants and from inside grass tussocks; the crake may search leaf litter with its bill, and run in pursuit of active prey. In Africa, both species will occasionally feed on grassy tracks or dirt roads. Plant material is eaten, especially grass seeds, but also green shoots, leaves and other seeds. As with other rails, grit is swallowed to help break up food in the stomach. Indigestible material is regurgitated as pellets
. Chicks are fed mainly on animal food. Crex crakes forage singly, in pairs or in family groups, sometimes in association with the other member of the genus or with other grassland birds such as Great Snipe
s, Blue Quail
s and Common Quails.
and domestic cat
s, introduced
American Mink
, feral Ferret
s, Otters
and Red Foxes
, and birds including the Common Buzzard
and Hooded Crow
. In Lithuania, the introduced Raccoon Dog
has also been recorded taking Corn Crakes. When chicks are exposed by rapid mowing, they may be taken by large birds including the White Stork
, harriers
and other birds of prey
, gull
s and corvids
.Koffijberg & Schaffer (2006) p. 21 At undisturbed sites, nests and broods are rarely attacked, which is reflected in the high breeding success.
In Africa, Crex species may be hunted by the Leopard
, Serval
, cat
s, the Black-headed Heron
, Dark Chanting Goshawk
, African Hawk-Eagle, Wahlberg's Eagle
,Taylor & van Perlo (2000) pp. 316–320 and Black Sparrowhawk.Taylor & van Perlo (2000) pp. 320–327 In South Africa, newly hatched African Crake chicks were taken by a Boomslang
.
Parasites recorded in this genus include the widespread fluke
Prosthogonimus ovatus( which lives in the oviduct
s of birds), the parasitic worm
Plagiorchis elegans, the larvae of parasitic flies, the feather mite
Metanalges elongatus, and hard ticks
of the genera Haemaphysalis
and Ixodes
. During the reintroduction of Corn Crakes to England in the 2003 breeding season, enteritis
and ill heath in pre-release birds was due to bacteria
of a pathogen
ic Campylobacter
species. Subsequently, microbiology
tests were done to detect infected individuals and to find the source of the bacteria in their environment.
on the IUCN Red List
. The Corn Crake was formerly classified as Near Threatened
because of serious declines in Europe, but improved monitoring in Russia indicates that anticipated losses there have not occurred and numbers have remained stable or possibly increased in Russia and Kazakhstan. Although most rails in the Old World are covered by the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA), neither Crex species is listed, being too terrestrial to be classed as wetland species.
Overgrazing, agriculture and the loss of wetland and moist grassland have reduced the availability of suitable habitat for the African Crake in many areas, such as some parts of the southern KwaZulu-Natal coast which have been urbanised or planted with sugarcane. In other areas, grassland may have increased locally in recent years as woodland is cleared. This crake is considered to be good eating, and is killed for food in some regions. Despite these adverse factors, it appears to be under no real threat.
In much of the western half of the Corn Crake's breeding range, there have been long-term declines that are expected to continue, although conservation measures have enabled numbers to grow in several countries, including substantial increases in the small populations in Finland, the UK and the Netherlands. The breeding population had begun to decline in the 19th century, but the process gained pace after World War II.Koffijberg & Schaffer (2006) p. 6 The main cause of the steep declines in much of Europe is the loss of nests and chicks from early mowing. Haymaking dates have moved forward in the past century due to faster crop growth, made possible by land drainage and the use of fertilisers, and the move from manual grass-cutting using scythes to mechanical mowers, at first horse-drawn and later pulled by tractors. Mechanisation also means that large areas can be cut quickly, leaving the crake with no alternative sites to raise either a first brood if suitable habitat has gone, or a replacement brood if the first nest is destroyed. The pattern of mowing, typically in a circular pattern from the outside of a field to its centre, gives little chance of escape for the chicks, which are also exposed to potential animal predators. Adults can often escape the mowers, although some incubating females sit tight on the nest, with fatal results.
Loss of habitat
is the other major threat to the Corn Crake, since drained and fertilised silage fields are less suitable for breeding than traditional hay meadows. In western Europe the conversion of grassland to arable land has been aided by subsidies, and further east the collapse of collective farming
has led to the abandonment and lack of management of much land in this important breeding area. More localised threats include floods in spring, and disturbance by roads or wind farm
s, and the loss of many birds – up to 14,000 a year – in Egypt, where migrating birds are captured in nets set for the quail with which they often migrate. Although this may account for 0.5–2.7% of the European population, the losses to this form of hunting are less than when the targeted species were more numerous and predictable.
Most European countries have taken steps to conserve the Corn Crake and produce national management policies; there is also an overall European action plan. The focus of conservation effort is to monitor populations and ecology
and to improve survival, principally through changing the timing and method of hay harvesting. Later cutting gives time for breeding to be completed, and leaving uncut strips at the edges of fields and cutting from the centre outwards reduces the casualties from mowing. Implementing these changes is predicted to stop the population decline if the measures are applied on a sufficiently large scale. Reduction of illegal hunting, and protection in countries where hunting is still allowed, are also conservation aims. Reintroduction of the Corn Crake is being attempted in England, and breeding sites are scheduled for protection in many other countries. Where breeding sites impinge on urban areas, there are cost implications, estimated in one German study at several million euros per Corn Crake. The Corn Crake does not appear to be seriously threatened on its wintering grounds and may benefit from deforestration, which creates more open habitats.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s in the rail family
Rallidae
The rails, or Rallidae, are a large cosmopolitan family of small to medium-sized birds. The family exhibits considerable diversity and the family also includes the crakes, coots, and gallinules...
. It contains two species, the Corn Crake
Corn Crake
The Corn Crake, Corncrake or Landrail is a bird in the rail family. It breeds in Europe and Asia as far east as western China, and migrates to Africa for the winter...
, C. crex, which breeds across Europe and Asia and winters in southern Africa, and the African Crake
African Crake
The African Crake is a bird in the rail family that breeds in most of sub-Saharan Africa away from the arid south and southwest. It is seasonally common in most of its range other than the rainforests and areas that have low annual rainfall...
, C. egregia, which migrates
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
within Africa. Both are short-billed rails with blackish-brown upperparts, mainly blue-grey underparts, and barring on the flanks. The Corn Crake is significantly larger than its relative, and has a distinctive chestnut
Chestnut (color)
Chestnut, also known as Indian red, is a color, a medium brownish shade of red, and is named after the nut of the chestnut tree.As Indian red, it is named after the red laterite soil found in India. It is thus an earth tone as well as a red. It is composed of naturally occurring iron oxides. Other...
patch on its wings. Unusually for their family, these are birds of dry habitats rather than wetlands; the Eurasian species mainly breeds in hay meadows, and the African Crake in dry grassland. The African Crake is sometimes given its own genus, Crecopsis, but is now more usually placed in Crex.
Both species have distinctive loud grating calls used for advertising and territorial purposes in the breeding season, although the Corn Crake is silent on its African wintering grounds. They are mainly active during the day; they walk with a high-stepping action, and when disturbed they can run swiftly through grass or fly a short distance to cover. Migration takes place at night, and the ability to undertake these journeys is innate, not learned from adults. The nest is a shallow cup of grass lined with finer vegetation and built in a well hidden depression. The precocial
Precocial
In biology, the term precocial refers to species in which the young are relatively mature and mobile from the moment of birth or hatching. The opposite developmental strategy is called "altricial," where the young are born or hatched helpless. Extremely precocial species may be called...
chicks leave the nest soon after hatching, and fledge
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...
after four to six weeks. These are ground-feeding omnivore
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...
s, but mainly eat invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s. They may be killed by a variety of mammals and large birds, and infected by parasites.
The two Crex species have huge breeding ranges and large populations and are classed as Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
. The Corn Crake was formerly classified as Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
because of serious declines in western Europe, but improved monitoring shows that numbers have remained stable further east in Russia and Kazakhstan. In much of the western half of the Corn Crake's breeding range, there have been long-term declines that are expected to continue. The main cause of the decline is the loss of nests and chicks from early mowing. Haymaking dates have moved forward in the past century due to faster crop growth, made possible by land drainage and the use of fertilisers, and the move from manual grass-cutting using scythe
Scythe
A scythe is an agricultural hand tool for mowing grass, or reaping crops. It was largely replaced by horse-drawn and then tractor machinery, but is still used in some areas of Europe and Asia. The Grim Reaper is often depicted carrying or wielding a scythe...
s to mechanical mower
Mower
A mower is a machine for cutting grass or other plants that grow on the ground. Usually mowing is distinguished from reaping, which uses similar implements, but is the traditional term for harvesting grain crops, e.g...
s. Loss of habitat
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
is the other major threat to the Corn Crake. Drained and fertilised silage fields are less suitable for breeding than traditional hay meadows. In western Europe the conversion of grassland to arable land has been aided by subsidies, and further east the collapse of collective farming
Collective farming
Collective farming and communal farming are types of agricultural production in which the holdings of several farmers are run as a joint enterprise...
has led to the abandonment and lack of management of much land in this important breeding area.
Taxonomy
The railsRallidae
The rails, or Rallidae, are a large cosmopolitan family of small to medium-sized birds. The family exhibits considerable diversity and the family also includes the crakes, coots, and gallinules...
are a bird family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
comprising nearly 150 species. Although the origins of the group are lost in antiquity, the largest number of species and the most primitive forms are found in the Old World
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....
, suggesting that this family originated there. The genus Crex was created by German naturalist and ornithologist Johann Matthäus Bechstein
Johann Matthäus Bechstein
Johann Matthäus Bechstein was a German naturalist, forester, ornithologist and entomologist. In Great Britain, he was known for his treatise on singing birds .-Biography:Bechstein was born in Waltershausen in the district of Gotha in Thuringia...
in 1803. Originally it held only the Corn Crake, C. crex, which Bechstein moved from its original name, Rallus crex, given to it by Linnaeus in his Systema Naturae
Systema Naturae
The book was one of the major works of the Swedish botanist, zoologist and physician Carolus Linnaeus. The first edition was published in 1735...
in 1758. The taxonomy of the small crakes is complicated, but the closest relative of the Corn Crake is the African Crake, C. egregia. This was first described as Ortygometra egregria by Wilhelm Peters
Wilhelm Peters
Wilhelm Karl Hartwich Peters was a German naturalist and explorer.He was assistant to Johannes Peter Müller and later curator of the Berlin Zoological Museum. In September 1842 he travelled to Mozambique via Angola. He returned to Berlin with an enormous collection of natural history specimens...
in 1854 from a specimen obtained in Mozambique, and has variously been placed in the genus Porzana
Porzana
Porzana is a genus of birds in the crake or rail family, Rallidae. It has a global distribution, contains 13 living species, and 4-5 recently extinct ones...
or its own genus, Crecopsis, but is now more usually placed in Crex. The Porzana
Porzana
Porzana is a genus of birds in the crake or rail family, Rallidae. It has a global distribution, contains 13 living species, and 4-5 recently extinct ones...
crakes are the closest relatives of the Crex genus, particularly the Ash-throated Crake
Ash-throated Crake
The Ash-throated Crake is a species of bird in the Rallidae family.It is found in Argentina, Bolivia, Brazil, Colombia, French Guiana, Guyana, Paraguay, Peru, Suriname, Trinidad and Tobago, and Venezuela....
, Porzana albicollis, which has occasionally also been allocated to Crex.
The genus name is onomatopoeic, referring to the repetitive grating call of the Corn Crake. Although these species occur in fairly open habitats, they lack the pure white undertail used for signalling in open water or gregarious species like the coot
Coot
Coots are medium-sized water birds that are members of the rail family Rallidae. They constitute the genus Fulica. Coots have predominantly black plumage, and, unlike many of the rails, they are usually easy to see, often swimming in open water...
s and moorhen
Moorhen
Moorhens, sometimes called marsh hens, are medium-sized water birds that are members of the rail family Rallidae. They constitute the genus Gallinula....
s.
Description
Sympatry
In biology, two species or populations are considered sympatric when they exist in the same geographic area and thus regularly encounter one another. An initially-interbreeding population that splits into two or more distinct species sharing a common range exemplifies sympatric speciation...
with the African Crake on its wintering grounds, but can be distinguished by its larger size, paler upperparts, chestnut-coloured patch on the upperwing and different underparts pattern. In flight, it has longer, less rounded wings, and shallower wingbeats than its African relative, and shows a white leading edge to the inner wing.
The sexes of each species are similar in appearance, although the females are slightly smaller and duller than the males, with a less contrasting head pattern. Juveniles of both species are duller than the adults, and browner underneath. Adults undergo a complete moult after breeding. No subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
have been recognised of either Crex crake. Although Corn Crakes become paler and greyer towards the east of the range, the change is clinal, and there is great individual variation in colour within all populations.
The two Crex crakes are unlikely to be confused with other rails, since most sympatric short-billed rails are smaller, with white markings on the upperparts, different underparts patterns and shorter bills. The European Water Rail
Water Rail
The Water Rail is a bird of the rail family which breeds in well-vegetated wetlands across Europe, Asia and North Africa. Northern and eastern populations are migratory, but this species is a permanent resident in the warmer parts of its breeding range...
and the African Rail
African Rail
The African Rail is a small wetland bird of the rail family.Its breeding habitat is marshes and reedbeds across eastern and southern Africa from Ethiopia to South Africa...
have long pointed bills.
Voice
Like other rails, the Crex species have a wide range of vocalisations. The males of both crakes have a loud territorial and advertising call consisting of a series of grating notes repeated two or three times a second for several minutes. The male stands upright with his neck extended when advertising, with its head and neck almost vertical and bill wide open. Calling is most frequent early in the breeding season, mainly at night for the Corn Crake, but in the day for its African cousin. The Corn Crake's call may be repeated more than 20,000 times a night, with a peak between midnight and 3 am.The advertising calls of both crakes are readily distinguished from the quite dissimilar calls of potentially sympatric
Sympatry
In biology, two species or populations are considered sympatric when they exist in the same geographic area and thus regularly encounter one another. An initially-interbreeding population that splits into two or more distinct species sharing a common range exemplifies sympatric speciation...
rails such as the Spotted Crake
Spotted Crake
The Spotted Crake is a small waterbird, of the family Rallidae.Their breeding habitat is marshes and sedge beds across temperate Europe into western Asia. They nest in a dry location in marsh vegetation, laying 6-15 eggs...
, Striped Crake
Striped Crake
The Striped Crake is a species of bird in the Rallidae family. It is the only species in the genus Aenigmatolimnas....
, Baillon's Crake
Baillon's Crake
The Baillon's Crake is a very small waterbird of the family Rallidae.-Distribution:Their breeding habitat is sedge beds in Europe, mainly in the east, and across Asia. They used to breed in Great Britain up to the mid-19th century, but the western European population declined through drainage....
, or Water Rail
Water Rail
The Water Rail is a bird of the rail family which breeds in well-vegetated wetlands across Europe, Asia and North Africa. Northern and eastern populations are migratory, but this species is a permanent resident in the warmer parts of its breeding range...
. The calls of the two Crex species cannot be confused, since the Corn Crake is silent in Africa. Both sexes may give distinctive territorial or alarm calls, and females and chicks communicate with cheeps and wheezes. The African Crake can be attracted to within 10 m (30 ft) of a human by imitation of its kraaa threat call, and the male Corn Crake by mechanical imitations of their advertising call, including rubbing a piece of wood down a notched stick, or by flicking a credit card against a comb or zip-fastener
Zipper
A zipper is a commonly used device for temporarily joining two edges of fabric...
.
Distribution and habitat
The Corn Crake is a long distance migrant, breeding across temperate Eurasia from the British IslesBritish Isles
The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...
east to central Siberia and western China. It winters in Africa from Zaire and central Tanzania south to eastern South Africa, mainly KwaZulu-Natal
KwaZulu-Natal
KwaZulu-Natal is a province of South Africa. Prior to 1994, the territory now known as KwaZulu-Natal was made up of the province of Natal and the homeland of KwaZulu....
and the former Transvaal Province
Transvaal Province
Transvaal Province was a province of the Union of South Africa from 1910 to 1961, and of its successor, the Republic of South Africa, from 1961 until the end of apartheid in 1994 when a new constitution subdivided it.-History:...
. Small numbers of birds may winter in the milder areas of western Europe, or halt their migration and stay in North Africa
North Africa
North Africa or Northern Africa is the northernmost region of the African continent, linked by the Sahara to Sub-Saharan Africa. Geopolitically, the United Nations definition of Northern Africa includes eight countries or territories; Algeria, Egypt, Libya, Morocco, South Sudan, Sudan, Tunisia, and...
.
The African Crake occurs throughout sub-Saharan Africa from Senegal east to Kenya and south to KwaZulu-Natal, except in arid areas of south and southwest Africa where the annual summer rainfall is less than 300 mm (11.8 in). It is widespread and locally common in most of its range, apart from the rainforest
Rainforest
Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...
s and the drier regions. Nearly all the South African population of about 8,000 birds occur in KwaZulu-Natal and the former Transvaal Province. This crake is only a vagrant
Vagrancy (biology)
Vagrancy is a phenomenon in biology whereby individual animals appear well outside their normal range; individual animals which exhibit vagrancy are known as vagrants. The term accidental is sometimes also used...
to the drier zones on the southern edges of South Africa's northern and eastern Cape Province
Cape Province
The Province of the Cape of Good Hope was a province in the Union of South Africa and subsequently the Republic of South Africa...
and North West Province
North West (South African province)
North West is a province of South Africa. Its capital is Mafikeng. The province is located to the west of the major population centre of Gauteng.-History:...
, and southern Botswana.
Both species are nocturnal migrants. Most Corn Crakes migrate through Egypt, with smaller numbers crossing at the western end of the Mediterranean
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
. It has been recorded in most countries between its breeding and wintering ranges, including much of west Africa, and those parts of southern Asia that lie between the east of the breeding range and Africa. Further afield, it has been recorded as a vagrant to Sri Lanka, Vietnam and Australia, the Seychelles, Bermuda, Canada, the United States, Greenland, and the North Atlantic islands.
The African species is a partial migrant
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
, but its movements are complex, seasonal and poorly studied. It is mainly a wet-season breeder, and many birds move away from the equator as soon as the rains provide sufficient grass cover to allow them to breed elsewhere. Southward movement is mainly from November to April, the return north beginning when burning or drought reduces the grass cover again. This species is present throughout the year in some West African countries, and in equatorial regions, but even in those areas numbers vary seasonally due to local movements; internal north–south migration has been noted within countries including Nigeria, Senegal, The Gambia, Ivory Coast and Cameroon. This crake has also wandered further afield. It is rare on Bioko Island
Bioko
Bioko is an island 32 km off the west coast of Africa, specifically Cameroon, in the Gulf of Guinea. It is the northernmost part of Equatorial Guinea with a population of 124,000 and an area of . It is volcanic with its highest peak the Pico Basile at .-Geography:Bioko has a total area of...
(Equatorial Guinea), and there have been two records each for São Tomé
São Tomé Island
São Tomé Island, at , is the largest island of São Tomé and Príncipe and is home in 2009 to about 157,000 or 96% of the nation's population. This island and smaller nearby islets make up São Tomé Province, which is divided into six districts. The main island is located 2 km north of the...
and Tenerife
Tenerife
Tenerife is the largest and most populous island of the seven Canary Islands, it is also the most populated island of Spain, with a land area of 2,034.38 km² and 906,854 inhabitants, 43% of the total population of the Canary Islands. About five million tourists visit Tenerife each year, the...
, the Canary Islands
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
birds being the first records for the Western Palaeartic.
Most rails are wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....
birds, but the two Crex species prefer drier habitats. The African Crake is found mainly in grassland, ranging from wetland edges and seasonal floodlands to savanna
Savanna
A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.Some...
, lightly wooded dry grassland, and grassy forest clearings. It also frequents maize, rice and cotton crops, derelict farmland and sugarcane plantations close to water. A wide range of grass species are used, with a preferred height of 0.3–1 m (1–3 ft) tall but vegetation is acceptable up to 2 m (6 ft) tall. The Corn Crake is mainly a lowland species, but breeds up to 1,400 m (4,600 ft) altitude in the Alps
Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....
, 2,700 m (8,600 ft) in China and 3,000 m (9,800 ft) in Russia. When breeding in Eurasia, the Corn Crake's habitats would originally have included river meadows with tall grass and meadow plants, but it is now mainly found in cool moist grassland used for the production of hay, particularly moist traditional farmland. It also utilises other treeless grasslands in mountains or taiga
Taiga
Taiga , also known as the boreal forest, is a biome characterized by coniferous forests.Taiga is the world's largest terrestrial biome. In North America it covers most of inland Canada and Alaska as well as parts of the extreme northern continental United States and is known as the Northwoods...
, on coasts, or where created by fire. Very wet habitats are avoided, as are open areas and those with vegetation more than 50 cm (20 in) tall, or too dense for the birds to walk through.
While wintering in Africa, the Corn Crake occupies dry grassland and savanna habitats, occurring in vegetation 30–200 cm (1–6 ft) tall, including seasonally burnt areas and occasionally sedges or reed bed
Reed bed
Reed beds are natural habitats found in floodplains, waterlogged depressions andestuaries. Reed beds are part of a succession from young reed colonising open water or wet ground through a gradation of increasingly dry ground...
s. It is also found on fallow and abandoned fields, uncut grass on airfields, and the edges of crops. It occurs at up to at least 1,750 m (5,700 ft) altitude in South Africa. Although it sometimes occurs with the African Crake, that species normally prefers moister and shorter grassland habitats than does the Corn Crake. On migration, the Corn Crake may also occur in wheatfields and around golf course
Golf course
A golf course comprises a series of holes, each consisting of a teeing ground, fairway, rough and other hazards, and a green with a flagstick and cup, all designed for the game of golf. A standard round of golf consists of playing 18 holes, thus most golf courses have this number of holes...
s.
Behaviour
Both Crex crakes are mainly active during the day, especially at dawn, dusk, during light rain, or after heavier rain. The African Crake is less skulking and easier to flush from cover than other crakes, and is often seen at the edges of roads and tracks, but the Corn Crake is a much more difficult bird to see in its breeding sites, usually being hidden by vegetation and rarely emerging into the open. Both crakes are territorial on both the breeding and non-breeding grounds; the male threat displays involves the bird standing upright and spreading the feathers of the wings, flanks and belly like a fan. Fighting at territorial boundaries involves the male birds jumping at each other and pecking.Both species walk with a high-stepping action, and can run swiftly through grass with the body held horizontal and laterally flattened. When disturbed, they typically fly less than 50 m (150 ft), frequently landing behind a bush or thicket, and then go into a crouch. In short grass, they can escape from a dog using their speed and maneuverability, running with the body held almost horizontal. The typical flight is weak and fluttering, especially that of the African Crake, but for longer flights, such as migration, the Corn Crake has a steadier, stronger action with its legs drawn up. Flocks of up to 40 Corn Crakes may form on migration, sometimes associating with Common Quail
Common Quail
The Common Quail, Coturnix coturnix, is a small bird in the pheasant family Phasianidae. It is widespread and is found in parts of Europe, .- Description :It is a small rotund bird, essentially streaked brown with...
s. Migration takes place at night, and flocks resting during the day may aggregate to hundreds of birds at favoured sites. The ability to migrate is innate, not learned from adults; chicks raised from birds kept in captivity for ten generations were able to migrate to Africa and return with similar success to wild-bred young.
Breeding
Both crakes were formerly believed to be monogamousMonogamy
Monogamy /Gr. μονός+γάμος - one+marriage/ a form of marriage in which an individual has only one spouse at any one time. In current usage monogamy often refers to having one sexual partner irrespective of marriage or reproduction...
, but the male Corn Crake may have a shifting home range, and mate with two or more females, moving on when laying is almost complete. The breeding display consists of a short chase of the female by the male. The nest is a shallow cup of grass leaves and lined with finer grasses, built in a depression and well hidden in the grass. The clutch
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...
size is from 3 to 11 pink eggs for the African species, and 6–14 – usually 8–12 – for the European breeder. The Corn Crake's eggs are oval, slightly glossy, creamy or tinted with green, blue or grey, and blotched red-brown. They average 37 × 26 mm, (1.5 × 1.0 in) and weigh about 13–16 g, (0.46–0.56 oz), of which 7% is shell.
The first egg is often laid when the nest is little more than a pad of grass, and a further egg is laid on each subsequent day. Both sexes incubate the eggs, which start hatching after about 14 days; all hatch with 48 hours despite the extended laying period. The black, downy precocial
Precocial
In biology, the term precocial refers to species in which the young are relatively mature and mobile from the moment of birth or hatching. The opposite developmental strategy is called "altricial," where the young are born or hatched helpless. Extremely precocial species may be called...
chicks soon leave the nest but are fed and protected by the parents. Fledging
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...
occurs after four to six weeks, and the young can fly before they are fully grown. It is not known whether the African Crake has a second brood, but the Corn Crake usually does. Where grass is not tall enough at the start of the season, the first nest may be constructed in herby or marsh vegetation, with the second brood in hay. The second nest may also be at a higher altitude that the first, to take advantage of the later-developing grasses further up a hill.
Although survival in undisturbed sites is high, at 80–90%, the Corn Crake suffers from modern farming practices, since mechanised mowing can kill 38–95% of chicks in a given site. The influence of weather on Corn Crake chick survival is limited: although chick growth is faster in dry or warm weather, the effects are relatively small. Unlike many precocial species, chicks are fed by their mother for a few days until they become independent, and this may cushion them from adverse conditions. The number of live chicks hatched is more important than the weather, with lower survival in large broods.
Feeding
Both Crex crakes are omnivorousOmnivore
Omnivores are species that eat both plants and animals as their primary food source...
, but mainly feed on invertebrates, including earthworm
Earthworm
Earthworm is the common name for the largest members of Oligochaeta in the phylum Annelida. In classical systems they were placed in the order Opisthopora, on the basis of the male pores opening posterior to the female pores, even though the internal male segments are anterior to the female...
s, slug
Slug
Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...
s and snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
s, spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
s, beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s, dragonflies
Dragonfly
A dragonfly is a winged insect belonging to the order Odonata, the suborder Epiprocta or, in the strict sense, the infraorder Anisoptera . It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body...
, grasshopper
Grasshopper
The grasshopper is an insect of the suborder Caelifera in the order Orthoptera. To distinguish it from bush crickets or katydids, it is sometimes referred to as the short-horned grasshopper...
s and other insects. The Corn Crake may take pests such as Sitona
Sitona
Sitona is a large genus of weevils in the family Curculionidae, native to the Nearctic and Palaearctic regions. More than 100 species have been described...
weevil
Weevil
A weevil is any beetle from the Curculionoidea superfamily. They are usually small, less than , and herbivorous. There are over 60,000 species in several families, mostly in the family Curculionidae...
s, leatherjacket
Crane fly
A crane fly is an insect in the family Tipulidae. Adults are very slender, long-legged flies that may vary in length from though tropical species may exceed to ....
s and wireworm
Click beetle
The family Elateridae is commonly called click beetles , elaters, snapping beetles, spring beetles or "skipjacks". They are a cosmopolitan beetle family characterized by the unusual click mechanism they possess...
s. In Africa, termite
Termite
Termites are a group of eusocial insects that, until recently, were classified at the taxonomic rank of order Isoptera , but are now accepted as the epifamily Termitoidae, of the cockroach order Blattodea...
s, cockroach
Cockroach
Cockroaches are insects of the order Blattaria or Blattodea, of which about 30 species out of 4,500 total are associated with human habitations...
es and dung beetle
Dung beetle
Dung beetles are beetles that feed partly or exclusively on feces. All of these species belong to the superfamily Scarabaeoidea; most of them to the subfamilies Scarabaeinae and Aphodiinae of the family Scarabaeidae. This beetle can also be referred to as the scarab beetle. As most species of...
s may be consumed. These opportunist hunters will take the occasional vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
such as a small frog, rodent or fish. Food is taken from the ground, low-growing plants and from inside grass tussocks; the crake may search leaf litter with its bill, and run in pursuit of active prey. In Africa, both species will occasionally feed on grassy tracks or dirt roads. Plant material is eaten, especially grass seeds, but also green shoots, leaves and other seeds. As with other rails, grit is swallowed to help break up food in the stomach. Indigestible material is regurgitated as pellets
Pellet (ornithology)
A pellet, in ornithology, is the mass of undigested parts of a bird's food that some bird species occasionally regurgitate. The contents of a bird's pellet depend on its diet, but can include the exoskeletons of insects, indigestible plant matter, bones, fur, feathers, bills, claws, and teeth...
. Chicks are fed mainly on animal food. Crex crakes forage singly, in pairs or in family groups, sometimes in association with the other member of the genus or with other grassland birds such as Great Snipe
Great Snipe
The Great Snipe, Gallinago media is a small stocky wader in the genus Gallinago.This bird's breeding habitat is marshes and wet meadows with short vegetation in north-eastern Europe including north-western Russia. Great Snipes are migratory, wintering in Africa...
s, Blue Quail
Blue Quail
The Blue Quail or African Blue Quail, is a species of bird in the Phasianidae family.-Geographic Range:The species ranges from Sierra Leone to Ethiopia, and south to Zambia, and eastward to Kenya, and is migratory...
s and Common Quails.
Predators and parasites
Predators of the Corn Crake on its European breeding grounds include feralFeral
A feral organism is one that has changed from being domesticated to being wild or untamed. In the case of plants it is a movement from cultivated to uncultivated or controlled to volunteer. The introduction of feral animals or plants to their non-native regions, like any introduced species, may...
and domestic cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s, introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
American Mink
American Mink
The American mink is a semi-aquatic species of Mustelid native to North America, though human intervention has expanded its range to many parts of Europe and South America. Because of this, it is classed as Least Concern by the IUCN. Since the extinction of the sea mink, the American mink is the...
, feral Ferret
Ferret
The ferret is a domesticated mammal of the type Mustela putorius furo. Ferrets are sexually dimorphic predators with males being substantially larger than females. They typically have brown, black, white, or mixed fur...
s, Otters
European Otter
The European Otter , also known as the Eurasian otter, Eurasian river otter, common otter and Old World otter, is a European and Asian member of the Lutrinae or otter subfamily, and is typical of freshwater otters....
and Red Foxes
Red Fox
The red fox is the largest of the true foxes, as well as being the most geographically spread member of the Carnivora, being distributed across the entire northern hemisphere from the Arctic Circle to North Africa, Central America, and the steppes of Asia...
, and birds including the Common Buzzard
Common Buzzard
The Common Buzzard is a medium to large bird of prey, whose range covers most of Europe and extends into Asia. It is usually resident all year, except in the coldest parts of its range, and in the case of one subspecies.-Description:...
and Hooded Crow
Hooded Crow
The Hooded Crow is a Eurasian bird species in the crow genus. Widely distributed, it is also known locally as Scotch Crow, Danish Crow, and Corbie or Grey Crow in Ireland, which is what its Welsh name, Brân Lwyd, translates as...
. In Lithuania, the introduced Raccoon Dog
Raccoon Dog
The raccoon dog , also known as the magnut or tanuki, is a canid indigenous to east Asia. It is the only extant species in the genus Nyctereutes...
has also been recorded taking Corn Crakes. When chicks are exposed by rapid mowing, they may be taken by large birds including the White Stork
White Stork
The White Stork is a large bird in the stork family Ciconiidae. Its plumage is mainly white, with black on its wings. Adults have long red legs and long pointed red beaks, and measure on average from beak tip to end of tail, with a wingspan...
, harriers
Harrier (bird)
A harrier is any of the several species of diurnal hawks forming the Circinae sub-family of the Accipitridae family of birds of prey. Harriers characteristically hunt by flying low over open ground, feeding on small mammals, reptiles, or birds....
and other birds of prey
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
, gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s and corvids
Corvidae
Corvidae is a cosmopolitan family of oscine passerine birds that contains the crows, ravens, rooks, jackdaws, jays, magpies, treepies, choughs and nutcrackers. The common English names used are corvids or the crow family , and there are over 120 species...
. At undisturbed sites, nests and broods are rarely attacked, which is reflected in the high breeding success.
In Africa, Crex species may be hunted by the Leopard
Leopard
The leopard , Panthera pardus, is a member of the Felidae family and the smallest of the four "big cats" in the genus Panthera, the other three being the tiger, lion, and jaguar. The leopard was once distributed across eastern and southern Asia and Africa, from Siberia to South Africa, but its...
, Serval
Serval
The serval , Leptailurus serval or Caracal serval, known in Afrikaans as Tierboskat, "tiger-forest-cat", is a medium-sized African wild cat. DNA studies have shown that the serval is closely related to the African golden cat and the caracal...
, cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s, the Black-headed Heron
Black-headed Heron
The Black-headed Heron is a wading bird of the heron family Ardeidae, common throughout much of sub-Saharan Africa and Madagascar. It is mainly resident but some west African birds move further north in the rainy season....
, Dark Chanting Goshawk
Dark Chanting Goshawk
The Dark Chanting Goshawk is a bird of prey in the family Accipitridae. The Accipitridae also include many other diurnal raptors such as kites, eagles and harriers....
, African Hawk-Eagle, Wahlberg's Eagle
Wahlberg's Eagle
The Wahlberg's Eagle is a bird of prey. It is about 55–60 cm in length and has a wingspan of 130–160 cm. Body mass is 1.04 kg for males and 1.3 kg for females on average. Like all eagles, it belongs to the family Accipitridae.Wahlberg's Eagle breeds in most of Africa south of...
, and Black Sparrowhawk. In South Africa, newly hatched African Crake chicks were taken by a Boomslang
Boomslang
The boomslang is a large venomous colubrid snake.-Taxonomy & etymology:It is currently the only species in its genus, although several species and subspecies have been described in the past...
.
Parasites recorded in this genus include the widespread fluke
Trematoda
Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:...
Prosthogonimus ovatus( which lives in the oviduct
Oviduct
In non-mammalian vertebrates, the passageway from the ovaries to the outside of the body is known as the oviduct. The eggs travel along the oviduct. These eggs will either be fertilized by sperm to become a zygote, or will degenerate in the body...
s of birds), the parasitic worm
Parasitic worm
Parasitic worms or helminths are a division of eukaryoticparasites that, unlike external parasites such as lice and fleas, live inside their host. They are worm-like organisms that live and feed off living hosts, receiving nourishment and protection while disrupting their hosts' nutrient...
Plagiorchis elegans, the larvae of parasitic flies, the feather mite
Feather mite
Feather mites are the members of diverse mite superfamilies:* superorder Acariformes** Psoroptidia*** Analgoidea*** Freyanoidea*** Pterolichoidea* superorder Parasitiformes** DermanyssoideaThey are ectoparasites on birds, hence the common name....
Metanalges elongatus, and hard ticks
Ixodidae
Ixodidae is a family of ticks containing the hard ticks.-Description:They are distinguished from the other main family of ticks, the soft ticks by the presence of a scutum or hard shield...
of the genera Haemaphysalis
Haemaphysalis
Haemaphysalis is a genus of tick.-Species:* Haemaphysalis aborensis Warburton, 1913* Haemaphysalis aciculifer Warburton 1913* Haemaphysalis aculeata Lavarra, 1904* Haemaphysalis adleri Feldman-Muhsam, 1951...
and Ixodes
Ixodes
Ixodes is a genus of hard-bodied ticks . It includes important disease vectors of animals and humans . Some ticks in this genus may transmit the pathogenic bacterium Borrelia burgdorferi responsible for causing Lyme disease...
. During the reintroduction of Corn Crakes to England in the 2003 breeding season, enteritis
Enteritis
In medicine, enteritis, from Greek words enteron and suffix -itis , refers to inflammation of the small intestine. It is most commonly caused by the ingestion of substances contaminated with pathogenic microorganisms. Symptoms include abdominal pain, cramping, diarrhea, dehydration and fever...
and ill heath in pre-release birds was due to bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
of a pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
ic Campylobacter
Campylobacter
Campylobacter is a genus of bacteria that are Gram-negative, spiral, and microaerophilic. Motile, with either unipolar or bipolar flagella, the organisms have a characteristic spiral/corkscrew appearance and are oxidase-positive. Campylobacter jejuni is now recognized as one of the main causes...
species. Subsequently, microbiology
Microbiology
Microbiology is the study of microorganisms, which are defined as any microscopic organism that comprises either a single cell , cell clusters or no cell at all . This includes eukaryotes, such as fungi and protists, and prokaryotes...
tests were done to detect infected individuals and to find the source of the bacteria in their environment.
Status
Both Crex species have huge breeding ranges, estimated at 15,700,000 km2 (4,500,000 mi2) for the African Crake and 12,400,000 km2 (4,800,000 mi2) for the Corn Crake. The population size of the African species is unknown, but it is common in most of its range, and its numbers appear to be stable. The European bird has an estimated 1.3–2.0 million breeding pairs in Europe, three-quarters of which are in European Russia, and a further 515,000–1,240,000 pairs in Asiatic Russia; the total Eurasian population has been estimated at between 5.45 and 9.72 million individuals. Both species are classed as Least ConcernLeast Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
. The Corn Crake was formerly classified as Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
because of serious declines in Europe, but improved monitoring in Russia indicates that anticipated losses there have not occurred and numbers have remained stable or possibly increased in Russia and Kazakhstan. Although most rails in the Old World are covered by the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA), neither Crex species is listed, being too terrestrial to be classed as wetland species.
Overgrazing, agriculture and the loss of wetland and moist grassland have reduced the availability of suitable habitat for the African Crake in many areas, such as some parts of the southern KwaZulu-Natal coast which have been urbanised or planted with sugarcane. In other areas, grassland may have increased locally in recent years as woodland is cleared. This crake is considered to be good eating, and is killed for food in some regions. Despite these adverse factors, it appears to be under no real threat.
In much of the western half of the Corn Crake's breeding range, there have been long-term declines that are expected to continue, although conservation measures have enabled numbers to grow in several countries, including substantial increases in the small populations in Finland, the UK and the Netherlands. The breeding population had begun to decline in the 19th century, but the process gained pace after World War II. The main cause of the steep declines in much of Europe is the loss of nests and chicks from early mowing. Haymaking dates have moved forward in the past century due to faster crop growth, made possible by land drainage and the use of fertilisers, and the move from manual grass-cutting using scythes to mechanical mowers, at first horse-drawn and later pulled by tractors. Mechanisation also means that large areas can be cut quickly, leaving the crake with no alternative sites to raise either a first brood if suitable habitat has gone, or a replacement brood if the first nest is destroyed. The pattern of mowing, typically in a circular pattern from the outside of a field to its centre, gives little chance of escape for the chicks, which are also exposed to potential animal predators. Adults can often escape the mowers, although some incubating females sit tight on the nest, with fatal results.
Loss of habitat
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
is the other major threat to the Corn Crake, since drained and fertilised silage fields are less suitable for breeding than traditional hay meadows. In western Europe the conversion of grassland to arable land has been aided by subsidies, and further east the collapse of collective farming
Collective farming
Collective farming and communal farming are types of agricultural production in which the holdings of several farmers are run as a joint enterprise...
has led to the abandonment and lack of management of much land in this important breeding area. More localised threats include floods in spring, and disturbance by roads or wind farm
Wind farm
A wind farm is a group of wind turbines in the same location used to produce electric power. A large wind farm may consist of several hundred individual wind turbines, and cover an extended area of hundreds of square miles, but the land between the turbines may be used for agricultural or other...
s, and the loss of many birds – up to 14,000 a year – in Egypt, where migrating birds are captured in nets set for the quail with which they often migrate. Although this may account for 0.5–2.7% of the European population, the losses to this form of hunting are less than when the targeted species were more numerous and predictable.
Most European countries have taken steps to conserve the Corn Crake and produce national management policies; there is also an overall European action plan. The focus of conservation effort is to monitor populations and ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
and to improve survival, principally through changing the timing and method of hay harvesting. Later cutting gives time for breeding to be completed, and leaving uncut strips at the edges of fields and cutting from the centre outwards reduces the casualties from mowing. Implementing these changes is predicted to stop the population decline if the measures are applied on a sufficiently large scale. Reduction of illegal hunting, and protection in countries where hunting is still allowed, are also conservation aims. Reintroduction of the Corn Crake is being attempted in England, and breeding sites are scheduled for protection in many other countries. Where breeding sites impinge on urban areas, there are cost implications, estimated in one German study at several million euros per Corn Crake. The Corn Crake does not appear to be seriously threatened on its wintering grounds and may benefit from deforestration, which creates more open habitats.
Crex is a small genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s in the rail family
Rallidae
The rails, or Rallidae, are a large cosmopolitan family of small to medium-sized birds. The family exhibits considerable diversity and the family also includes the crakes, coots, and gallinules...
. It contains two species, the Corn Crake
Corn Crake
The Corn Crake, Corncrake or Landrail is a bird in the rail family. It breeds in Europe and Asia as far east as western China, and migrates to Africa for the winter...
, C. crex, which breeds across Europe and Asia and winters in southern Africa, and the African Crake
African Crake
The African Crake is a bird in the rail family that breeds in most of sub-Saharan Africa away from the arid south and southwest. It is seasonally common in most of its range other than the rainforests and areas that have low annual rainfall...
, C. egregia, which migrates
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
within Africa. Both are short-billed rails with blackish-brown upperparts, mainly blue-grey underparts, and barring on the flanks. The Corn Crake is significantly larger than its relative, and has a distinctive chestnut
Chestnut (color)
Chestnut, also known as Indian red, is a color, a medium brownish shade of red, and is named after the nut of the chestnut tree.As Indian red, it is named after the red laterite soil found in India. It is thus an earth tone as well as a red. It is composed of naturally occurring iron oxides. Other...
patch on its wings. Unusually for their family, these are birds of dry habitats rather than wetlands; the Eurasian species mainly breeds in hay meadows, and the African Crake in dry grassland. The African Crake is sometimes given its own genus, Crecopsis, but is now more usually placed in Crex.
Both species have distinctive loud grating calls used for advertising and territorial purposes in the breeding season, although the Corn Crake is silent on its African wintering grounds. They are mainly active during the day; they walk with a high-stepping action, and when disturbed they can run swiftly through grass or fly a short distance to cover. Migration takes place at night, and the ability to undertake these journeys is innate, not learned from adults. The nest is a shallow cup of grass lined with finer vegetation and built in a well hidden depression. The precocial
Precocial
In biology, the term precocial refers to species in which the young are relatively mature and mobile from the moment of birth or hatching. The opposite developmental strategy is called "altricial," where the young are born or hatched helpless. Extremely precocial species may be called...
chicks leave the nest soon after hatching, and fledge
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...
after four to six weeks. These are ground-feeding omnivore
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...
s, but mainly eat invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s. They may be killed by a variety of mammals and large birds, and infected by parasites.
The two Crex species have huge breeding ranges and large populations and are classed as Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
. The Corn Crake was formerly classified as Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
because of serious declines in western Europe, but improved monitoring shows that numbers have remained stable further east in Russia and Kazakhstan. In much of the western half of the Corn Crake's breeding range, there have been long-term declines that are expected to continue. The main cause of the decline is the loss of nests and chicks from early mowing. Haymaking dates have moved forward in the past century due to faster crop growth, made possible by land drainage and the use of fertilisers, and the move from manual grass-cutting using scythe
Scythe
A scythe is an agricultural hand tool for mowing grass, or reaping crops. It was largely replaced by horse-drawn and then tractor machinery, but is still used in some areas of Europe and Asia. The Grim Reaper is often depicted carrying or wielding a scythe...
s to mechanical mower
Mower
A mower is a machine for cutting grass or other plants that grow on the ground. Usually mowing is distinguished from reaping, which uses similar implements, but is the traditional term for harvesting grain crops, e.g...
s. Loss of habitat
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
is the other major threat to the Corn Crake. Drained and fertilised silage fields are less suitable for breeding than traditional hay meadows. In western Europe the conversion of grassland to arable land has been aided by subsidies, and further east the collapse of collective farming
Collective farming
Collective farming and communal farming are types of agricultural production in which the holdings of several farmers are run as a joint enterprise...
has led to the abandonment and lack of management of much land in this important breeding area.
Taxonomy
The railsRallidae
The rails, or Rallidae, are a large cosmopolitan family of small to medium-sized birds. The family exhibits considerable diversity and the family also includes the crakes, coots, and gallinules...
are a bird family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
comprising nearly 150 species. Although the origins of the group are lost in antiquity, the largest number of species and the most primitive forms are found in the Old World
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....
, suggesting that this family originated there. The genus Crex was created by German naturalist and ornithologist Johann Matthäus Bechstein
Johann Matthäus Bechstein
Johann Matthäus Bechstein was a German naturalist, forester, ornithologist and entomologist. In Great Britain, he was known for his treatise on singing birds .-Biography:Bechstein was born in Waltershausen in the district of Gotha in Thuringia...
in 1803. Originally it held only the Corn Crake, C. crex, which Bechstein moved from its original name, Rallus crex, given to it by Linnaeus in his Systema Naturae
Systema Naturae
The book was one of the major works of the Swedish botanist, zoologist and physician Carolus Linnaeus. The first edition was published in 1735...
in 1758. The taxonomy of the small crakes is complicated, but the closest relative of the Corn Crake is the African Crake, C. egregia. This was first described as Ortygometra egregria by Wilhelm Peters
Wilhelm Peters
Wilhelm Karl Hartwich Peters was a German naturalist and explorer.He was assistant to Johannes Peter Müller and later curator of the Berlin Zoological Museum. In September 1842 he travelled to Mozambique via Angola. He returned to Berlin with an enormous collection of natural history specimens...
in 1854 from a specimen obtained in Mozambique, and has variously been placed in the genus Porzana
Porzana
Porzana is a genus of birds in the crake or rail family, Rallidae. It has a global distribution, contains 13 living species, and 4-5 recently extinct ones...
or its own genus, Crecopsis, but is now more usually placed in Crex.Taylor & van Perlo (2000) p. 30Livezey (1998) p. 2098 The Porzana
Porzana
Porzana is a genus of birds in the crake or rail family, Rallidae. It has a global distribution, contains 13 living species, and 4-5 recently extinct ones...
crakes are the closest relatives of the Crex genus, particularly the Ash-throated Crake
Ash-throated Crake
The Ash-throated Crake is a species of bird in the Rallidae family.It is found in Argentina, Bolivia, Brazil, Colombia, French Guiana, Guyana, Paraguay, Peru, Suriname, Trinidad and Tobago, and Venezuela....
, Porzana albicollis, which has occasionally also been allocated to Crex.Livezey (1998) p. 2134
The genus name is onomatopoeic, referring to the repetitive grating call of the Corn Crake. Although these species occur in fairly open habitats, they lack the pure white undertail used for signalling in open water or gregarious species like the coot
Coot
Coots are medium-sized water birds that are members of the rail family Rallidae. They constitute the genus Fulica. Coots have predominantly black plumage, and, unlike many of the rails, they are usually easy to see, often swimming in open water...
s and moorhen
Moorhen
Moorhens, sometimes called marsh hens, are medium-sized water birds that are members of the rail family Rallidae. They constitute the genus Gallinula....
s.
Description
Sympatry
In biology, two species or populations are considered sympatric when they exist in the same geographic area and thus regularly encounter one another. An initially-interbreeding population that splits into two or more distinct species sharing a common range exemplifies sympatric speciation...
with the African Crake on its wintering grounds, but can be distinguished by its larger size, paler upperparts, chestnut-coloured patch on the upperwing and different underparts pattern. In flight, it has longer, less rounded wings, and shallower wingbeats than its African relative, and shows a white leading edge to the inner wing.
The sexes of each species are similar in appearance, although the females are slightly smaller and duller than the males, with a less contrasting head pattern. Juveniles of both species are duller than the adults, and browner underneath. Adults undergo a complete moult after breeding. No subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
have been recognised of either Crex crake. Although Corn Crakes become paler and greyer towards the east of the range, the change is clinal, and there is great individual variation in colour within all populations.
The two Crex crakes are unlikely to be confused with other rails, since most sympatric short-billed rails are smaller, with white markings on the upperparts, different underparts patterns and shorter bills. The European Water Rail
Water Rail
The Water Rail is a bird of the rail family which breeds in well-vegetated wetlands across Europe, Asia and North Africa. Northern and eastern populations are migratory, but this species is a permanent resident in the warmer parts of its breeding range...
and the African Rail
African Rail
The African Rail is a small wetland bird of the rail family.Its breeding habitat is marshes and reedbeds across eastern and southern Africa from Ethiopia to South Africa...
have long pointed bills.
Voice
Like other rails, the Crex species have a wide range of vocalisations. The males of both crakes have a loud territorial and advertising call consisting of a series of grating notes repeated two or three times a second for several minutes. The male stands upright with his neck extended when advertising, with its head and neck almost vertical and bill wide open. Calling is most frequent early in the breeding season, mainly at night for the Corn Crake, but in the day for its African cousin. The Corn Crake's call may be repeated more than 20,000 times a night, with a peak between midnight and 3 am.The advertising calls of both crakes are readily distinguished from the quite dissimilar calls of potentially sympatric
Sympatry
In biology, two species or populations are considered sympatric when they exist in the same geographic area and thus regularly encounter one another. An initially-interbreeding population that splits into two or more distinct species sharing a common range exemplifies sympatric speciation...
rails such as the Spotted Crake
Spotted Crake
The Spotted Crake is a small waterbird, of the family Rallidae.Their breeding habitat is marshes and sedge beds across temperate Europe into western Asia. They nest in a dry location in marsh vegetation, laying 6-15 eggs...
, Striped Crake
Striped Crake
The Striped Crake is a species of bird in the Rallidae family. It is the only species in the genus Aenigmatolimnas....
, Baillon's Crake
Baillon's Crake
The Baillon's Crake is a very small waterbird of the family Rallidae.-Distribution:Their breeding habitat is sedge beds in Europe, mainly in the east, and across Asia. They used to breed in Great Britain up to the mid-19th century, but the western European population declined through drainage....
, or Water Rail
Water Rail
The Water Rail is a bird of the rail family which breeds in well-vegetated wetlands across Europe, Asia and North Africa. Northern and eastern populations are migratory, but this species is a permanent resident in the warmer parts of its breeding range...
.Taylor & van Perlo (2000) pp. 293–299 The calls of the two Crex species cannot be confused, since the Corn Crake is silent in Africa. Both sexes may give distinctive territorial or alarm calls, and females and chicks communicate with cheeps and wheezes. The African Crake can be attracted to within 10 m (30 ft) of a human by imitation of its kraaa threat call, and the male Corn Crake by mechanical imitations of their advertising call, including rubbing a piece of wood down a notched stick, or by flicking a credit card against a comb or zip-fastener
Zipper
A zipper is a commonly used device for temporarily joining two edges of fabric...
.
Distribution and habitat
The Corn Crake is a long distance migrant, breeding across temperate Eurasia from the British IslesBritish Isles
The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...
east to central Siberia and western China. It winters in Africa from Zaire and central Tanzania south to eastern South Africa, mainly KwaZulu-Natal
KwaZulu-Natal
KwaZulu-Natal is a province of South Africa. Prior to 1994, the territory now known as KwaZulu-Natal was made up of the province of Natal and the homeland of KwaZulu....
and the former Transvaal Province
Transvaal Province
Transvaal Province was a province of the Union of South Africa from 1910 to 1961, and of its successor, the Republic of South Africa, from 1961 until the end of apartheid in 1994 when a new constitution subdivided it.-History:...
. Small numbers of birds may winter in the milder areas of western Europe, or halt their migration and stay in North Africa
North Africa
North Africa or Northern Africa is the northernmost region of the African continent, linked by the Sahara to Sub-Saharan Africa. Geopolitically, the United Nations definition of Northern Africa includes eight countries or territories; Algeria, Egypt, Libya, Morocco, South Sudan, Sudan, Tunisia, and...
.
The African Crake occurs throughout sub-Saharan Africa from Senegal east to Kenya and south to KwaZulu-Natal, except in arid areas of south and southwest Africa where the annual summer rainfall is less than 300 mm (11.8 in). It is widespread and locally common in most of its range, apart from the rainforest
Rainforest
Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...
s and the drier regions. Nearly all the South African population of about 8,000 birds occur in KwaZulu-Natal and the former Transvaal Province. This crake is only a vagrant
Vagrancy (biology)
Vagrancy is a phenomenon in biology whereby individual animals appear well outside their normal range; individual animals which exhibit vagrancy are known as vagrants. The term accidental is sometimes also used...
to the drier zones on the southern edges of South Africa's northern and eastern Cape Province
Cape Province
The Province of the Cape of Good Hope was a province in the Union of South Africa and subsequently the Republic of South Africa...
and North West Province
North West (South African province)
North West is a province of South Africa. Its capital is Mafikeng. The province is located to the west of the major population centre of Gauteng.-History:...
, and southern Botswana. Retrieved 26 May 2011
Both species are nocturnal migrants. Most Corn Crakes migrate through Egypt, with smaller numbers crossing at the western end of the Mediterranean
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
. It has been recorded in most countries between its breeding and wintering ranges, including much of west Africa, and those parts of southern Asia that lie between the east of the breeding range and Africa. Further afield, it has been recorded as a vagrant to Sri Lanka, Vietnam and Australia,Bräunlich, Axel; Rank, Michael (2001)Notes on the occurrence of the Corncrake (Crex crex) in Asia and in the Pacific region pp. 10–13 in Schäffer, N; Mammen, U (eds.) (2001) Proceedings International Corncrake Workshop 1998, Hilpoltstein/Germany. the Seychelles, Bermuda, Canada, the United States, Greenland, and the North Atlantic islands.
The African species is a partial migrant
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
, but its movements are complex, seasonal and poorly studied. It is mainly a wet-season breeder, and many birds move away from the equator as soon as the rains provide sufficient grass cover to allow them to breed elsewhere. Southward movement is mainly from November to April, the return north beginning when burning or drought reduces the grass cover again. This species is present throughout the year in some West African countries, and in equatorial regions, but even in those areas numbers vary seasonally due to local movements; internal north–south migration has been noted within countries including Nigeria, Senegal, The Gambia, Ivory Coast and Cameroon. This crake has also wandered further afield. It is rare on Bioko Island
Bioko
Bioko is an island 32 km off the west coast of Africa, specifically Cameroon, in the Gulf of Guinea. It is the northernmost part of Equatorial Guinea with a population of 124,000 and an area of . It is volcanic with its highest peak the Pico Basile at .-Geography:Bioko has a total area of...
(Equatorial Guinea),Larison, Brenda; Smith, Thomas B; Milá, Borja; Stauffer, Donald; Nguema, José (1999) " Bird and Mammal Surveys of Rio Muni" pp. 9–57 in and there have been two records each for São Tomé
São Tomé Island
São Tomé Island, at , is the largest island of São Tomé and Príncipe and is home in 2009 to about 157,000 or 96% of the nation's population. This island and smaller nearby islets make up São Tomé Province, which is divided into six districts. The main island is located 2 km north of the...
and Tenerife
Tenerife
Tenerife is the largest and most populous island of the seven Canary Islands, it is also the most populated island of Spain, with a land area of 2,034.38 km² and 906,854 inhabitants, 43% of the total population of the Canary Islands. About five million tourists visit Tenerife each year, the...
, the Canary Islands
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
birds being the first records for the Western Palaeartic.
Most rails are wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....
birds, but the two Crex species prefer drier habitats. The African Crake is found mainly in grassland, ranging from wetland edges and seasonal floodlands to savanna
Savanna
A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.Some...
, lightly wooded dry grassland, and grassy forest clearings. It also frequents maize, rice and cotton crops, derelict farmland and sugarcane plantations close to water. A wide range of grass species are used, with a preferred height of 0.3–1 m (1–3 ft) tall but vegetation is acceptable up to 2 m (6 ft) tall. The Corn Crake is mainly a lowland species, but breeds up to 1,400 m (4,600 ft) altitude in the Alps
Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....
, 2,700 m (8,600 ft) in China and 3,000 m (9,800 ft) in Russia. When breeding in Eurasia, the Corn Crake's habitats would originally have included river meadows with tall grass and meadow plants, but it is now mainly found in cool moist grassland used for the production of hay, particularly moist traditional farmland. It also utilises other treeless grasslands in mountains or taiga
Taiga
Taiga , also known as the boreal forest, is a biome characterized by coniferous forests.Taiga is the world's largest terrestrial biome. In North America it covers most of inland Canada and Alaska as well as parts of the extreme northern continental United States and is known as the Northwoods...
, on coasts, or where created by fire. Very wet habitats are avoided, as are open areas and those with vegetation more than 50 cm (20 in) tall, or too dense for the birds to walk through.
While wintering in Africa, the Corn Crake occupies dry grassland and savanna habitats, occurring in vegetation 30–200 cm (1–6 ft) tall, including seasonally burnt areas and occasionally sedges or reed bed
Reed bed
Reed beds are natural habitats found in floodplains, waterlogged depressions andestuaries. Reed beds are part of a succession from young reed colonising open water or wet ground through a gradation of increasingly dry ground...
s. It is also found on fallow and abandoned fields, uncut grass on airfields, and the edges of crops. It occurs at up to at least 1,750 m (5,700 ft) altitude in South Africa. Although it sometimes occurs with the African Crake, that species normally prefers moister and shorter grassland habitats than does the Corn Crake. On migration, the Corn Crake may also occur in wheatfields and around golf course
Golf course
A golf course comprises a series of holes, each consisting of a teeing ground, fairway, rough and other hazards, and a green with a flagstick and cup, all designed for the game of golf. A standard round of golf consists of playing 18 holes, thus most golf courses have this number of holes...
s.
Behaviour
Both Crex crakes are mainly active during the day, especially at dawn, dusk, during light rain, or after heavier rain. The African Crake is less skulking and easier to flush from cover than other crakes, and is often seen at the edges of roads and tracks, but the Corn Crake is a much more difficult bird to see in its breeding sites, usually being hidden by vegetation and rarely emerging into the open. Both crakes are territorial on both the breeding and non-breeding grounds; the male threat displays involves the bird standing upright and spreading the feathers of the wings, flanks and belly like a fan. Fighting at territorial boundaries involves the male birds jumping at each other and pecking.Both species walk with a high-stepping action, and can run swiftly through grass with the body held horizontal and laterally flattened. When disturbed, they typically fly less than 50 m (150 ft), frequently landing behind a bush or thicket, and then go into a crouch. In short grass, they can escape from a dog using their speed and maneuverability, running with the body held almost horizontal. The typical flight is weak and fluttering, especially that of the African Crake, but for longer flights, such as migration, the Corn Crake has a steadier, stronger action with its legs drawn up. Flocks of up to 40 Corn Crakes may form on migration, sometimes associating with Common Quail
Common Quail
The Common Quail, Coturnix coturnix, is a small bird in the pheasant family Phasianidae. It is widespread and is found in parts of Europe, .- Description :It is a small rotund bird, essentially streaked brown with...
s. Migration takes place at night, and flocks resting during the day may aggregate to hundreds of birds at favoured sites. The ability to migrate is innate, not learned from adults; chicks raised from birds kept in captivity for ten generations were able to migrate to Africa and return with similar success to wild-bred young.
Breeding
Both crakes were formerly believed to be monogamousMonogamy
Monogamy /Gr. μονός+γάμος - one+marriage/ a form of marriage in which an individual has only one spouse at any one time. In current usage monogamy often refers to having one sexual partner irrespective of marriage or reproduction...
, but the male Corn Crake may have a shifting home range, and mate with two or more females, moving on when laying is almost complete. The breeding display consists of a short chase of the female by the male. The nest is a shallow cup of grass leaves and lined with finer grasses, built in a depression and well hidden in the grass. The clutch
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...
size is from 3 to 11 pink eggs for the African species, and 6–14 – usually 8–12 – for the European breeder. The Corn Crake's eggs are oval, slightly glossy, creamy or tinted with green, blue or grey, and blotched red-brown. They average 37 × 26 mm, (1.5 × 1.0 in) and weigh about 13–16 g, (0.46–0.56 oz), of which 7% is shell.
The first egg is often laid when the nest is little more than a pad of grass, and a further egg is laid on each subsequent day. Both sexes incubate the eggs, which start hatching after about 14 days; all hatch with 48 hours despite the extended laying period. The black, downy precocial
Precocial
In biology, the term precocial refers to species in which the young are relatively mature and mobile from the moment of birth or hatching. The opposite developmental strategy is called "altricial," where the young are born or hatched helpless. Extremely precocial species may be called...
chicks soon leave the nest but are fed and protected by the parents. Fledging
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...
occurs after four to six weeks, and the young can fly before they are fully grown. It is not known whether the African Crake has a second brood, but the Corn Crake usually does. Where grass is not tall enough at the start of the season, the first nest may be constructed in herby or marsh vegetation, with the second brood in hay. The second nest may also be at a higher altitude that the first, to take advantage of the later-developing grasses further up a hill.
Although survival in undisturbed sites is high, at 80–90%, the Corn Crake suffers from modern farming practices, since mechanised mowing can kill 38–95% of chicks in a given site. The influence of weather on Corn Crake chick survival is limited: although chick growth is faster in dry or warm weather, the effects are relatively small. Unlike many precocial species, chicks are fed by their mother for a few days until they become independent, and this may cushion them from adverse conditions. The number of live chicks hatched is more important than the weather, with lower survival in large broods.
Feeding
Both Crex crakes are omnivorousOmnivore
Omnivores are species that eat both plants and animals as their primary food source...
, but mainly feed on invertebrates, including earthworm
Earthworm
Earthworm is the common name for the largest members of Oligochaeta in the phylum Annelida. In classical systems they were placed in the order Opisthopora, on the basis of the male pores opening posterior to the female pores, even though the internal male segments are anterior to the female...
s, slug
Slug
Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...
s and snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
s, spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
s, beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s, dragonflies
Dragonfly
A dragonfly is a winged insect belonging to the order Odonata, the suborder Epiprocta or, in the strict sense, the infraorder Anisoptera . It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body...
, grasshopper
Grasshopper
The grasshopper is an insect of the suborder Caelifera in the order Orthoptera. To distinguish it from bush crickets or katydids, it is sometimes referred to as the short-horned grasshopper...
s and other insects. The Corn Crake may take pests such as Sitona
Sitona
Sitona is a large genus of weevils in the family Curculionidae, native to the Nearctic and Palaearctic regions. More than 100 species have been described...
weevil
Weevil
A weevil is any beetle from the Curculionoidea superfamily. They are usually small, less than , and herbivorous. There are over 60,000 species in several families, mostly in the family Curculionidae...
s, leatherjacket
Crane fly
A crane fly is an insect in the family Tipulidae. Adults are very slender, long-legged flies that may vary in length from though tropical species may exceed to ....
s and wireworm
Click beetle
The family Elateridae is commonly called click beetles , elaters, snapping beetles, spring beetles or "skipjacks". They are a cosmopolitan beetle family characterized by the unusual click mechanism they possess...
s. In Africa, termite
Termite
Termites are a group of eusocial insects that, until recently, were classified at the taxonomic rank of order Isoptera , but are now accepted as the epifamily Termitoidae, of the cockroach order Blattodea...
s, cockroach
Cockroach
Cockroaches are insects of the order Blattaria or Blattodea, of which about 30 species out of 4,500 total are associated with human habitations...
es and dung beetle
Dung beetle
Dung beetles are beetles that feed partly or exclusively on feces. All of these species belong to the superfamily Scarabaeoidea; most of them to the subfamilies Scarabaeinae and Aphodiinae of the family Scarabaeidae. This beetle can also be referred to as the scarab beetle. As most species of...
s may be consumed. These opportunist hunters will take the occasional vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
such as a small frog, rodent or fish. Food is taken from the ground, low-growing plants and from inside grass tussocks; the crake may search leaf litter with its bill, and run in pursuit of active prey. In Africa, both species will occasionally feed on grassy tracks or dirt roads. Plant material is eaten, especially grass seeds, but also green shoots, leaves and other seeds. As with other rails, grit is swallowed to help break up food in the stomach. Indigestible material is regurgitated as pellets
Pellet (ornithology)
A pellet, in ornithology, is the mass of undigested parts of a bird's food that some bird species occasionally regurgitate. The contents of a bird's pellet depend on its diet, but can include the exoskeletons of insects, indigestible plant matter, bones, fur, feathers, bills, claws, and teeth...
. Chicks are fed mainly on animal food. Crex crakes forage singly, in pairs or in family groups, sometimes in association with the other member of the genus or with other grassland birds such as Great Snipe
Great Snipe
The Great Snipe, Gallinago media is a small stocky wader in the genus Gallinago.This bird's breeding habitat is marshes and wet meadows with short vegetation in north-eastern Europe including north-western Russia. Great Snipes are migratory, wintering in Africa...
s, Blue Quail
Blue Quail
The Blue Quail or African Blue Quail, is a species of bird in the Phasianidae family.-Geographic Range:The species ranges from Sierra Leone to Ethiopia, and south to Zambia, and eastward to Kenya, and is migratory...
s and Common Quails.
Predators and parasites
Predators of the Corn Crake on its European breeding grounds include feralFeral
A feral organism is one that has changed from being domesticated to being wild or untamed. In the case of plants it is a movement from cultivated to uncultivated or controlled to volunteer. The introduction of feral animals or plants to their non-native regions, like any introduced species, may...
and domestic cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s, introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
American Mink
American Mink
The American mink is a semi-aquatic species of Mustelid native to North America, though human intervention has expanded its range to many parts of Europe and South America. Because of this, it is classed as Least Concern by the IUCN. Since the extinction of the sea mink, the American mink is the...
, feral Ferret
Ferret
The ferret is a domesticated mammal of the type Mustela putorius furo. Ferrets are sexually dimorphic predators with males being substantially larger than females. They typically have brown, black, white, or mixed fur...
s, Otters
European Otter
The European Otter , also known as the Eurasian otter, Eurasian river otter, common otter and Old World otter, is a European and Asian member of the Lutrinae or otter subfamily, and is typical of freshwater otters....
and Red Foxes
Red Fox
The red fox is the largest of the true foxes, as well as being the most geographically spread member of the Carnivora, being distributed across the entire northern hemisphere from the Arctic Circle to North Africa, Central America, and the steppes of Asia...
, and birds including the Common Buzzard
Common Buzzard
The Common Buzzard is a medium to large bird of prey, whose range covers most of Europe and extends into Asia. It is usually resident all year, except in the coldest parts of its range, and in the case of one subspecies.-Description:...
and Hooded Crow
Hooded Crow
The Hooded Crow is a Eurasian bird species in the crow genus. Widely distributed, it is also known locally as Scotch Crow, Danish Crow, and Corbie or Grey Crow in Ireland, which is what its Welsh name, Brân Lwyd, translates as...
. In Lithuania, the introduced Raccoon Dog
Raccoon Dog
The raccoon dog , also known as the magnut or tanuki, is a canid indigenous to east Asia. It is the only extant species in the genus Nyctereutes...
has also been recorded taking Corn Crakes. When chicks are exposed by rapid mowing, they may be taken by large birds including the White Stork
White Stork
The White Stork is a large bird in the stork family Ciconiidae. Its plumage is mainly white, with black on its wings. Adults have long red legs and long pointed red beaks, and measure on average from beak tip to end of tail, with a wingspan...
, harriers
Harrier (bird)
A harrier is any of the several species of diurnal hawks forming the Circinae sub-family of the Accipitridae family of birds of prey. Harriers characteristically hunt by flying low over open ground, feeding on small mammals, reptiles, or birds....
and other birds of prey
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
, gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s and corvids
Corvidae
Corvidae is a cosmopolitan family of oscine passerine birds that contains the crows, ravens, rooks, jackdaws, jays, magpies, treepies, choughs and nutcrackers. The common English names used are corvids or the crow family , and there are over 120 species...
.Koffijberg & Schaffer (2006) p. 21 At undisturbed sites, nests and broods are rarely attacked, which is reflected in the high breeding success.
In Africa, Crex species may be hunted by the Leopard
Leopard
The leopard , Panthera pardus, is a member of the Felidae family and the smallest of the four "big cats" in the genus Panthera, the other three being the tiger, lion, and jaguar. The leopard was once distributed across eastern and southern Asia and Africa, from Siberia to South Africa, but its...
, Serval
Serval
The serval , Leptailurus serval or Caracal serval, known in Afrikaans as Tierboskat, "tiger-forest-cat", is a medium-sized African wild cat. DNA studies have shown that the serval is closely related to the African golden cat and the caracal...
, cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s, the Black-headed Heron
Black-headed Heron
The Black-headed Heron is a wading bird of the heron family Ardeidae, common throughout much of sub-Saharan Africa and Madagascar. It is mainly resident but some west African birds move further north in the rainy season....
, Dark Chanting Goshawk
Dark Chanting Goshawk
The Dark Chanting Goshawk is a bird of prey in the family Accipitridae. The Accipitridae also include many other diurnal raptors such as kites, eagles and harriers....
, African Hawk-Eagle, Wahlberg's Eagle
Wahlberg's Eagle
The Wahlberg's Eagle is a bird of prey. It is about 55–60 cm in length and has a wingspan of 130–160 cm. Body mass is 1.04 kg for males and 1.3 kg for females on average. Like all eagles, it belongs to the family Accipitridae.Wahlberg's Eagle breeds in most of Africa south of...
,Taylor & van Perlo (2000) pp. 316–320 and Black Sparrowhawk.Taylor & van Perlo (2000) pp. 320–327 In South Africa, newly hatched African Crake chicks were taken by a Boomslang
Boomslang
The boomslang is a large venomous colubrid snake.-Taxonomy & etymology:It is currently the only species in its genus, although several species and subspecies have been described in the past...
.
Parasites recorded in this genus include the widespread fluke
Trematoda
Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:...
Prosthogonimus ovatus( which lives in the oviduct
Oviduct
In non-mammalian vertebrates, the passageway from the ovaries to the outside of the body is known as the oviduct. The eggs travel along the oviduct. These eggs will either be fertilized by sperm to become a zygote, or will degenerate in the body...
s of birds), the parasitic worm
Parasitic worm
Parasitic worms or helminths are a division of eukaryoticparasites that, unlike external parasites such as lice and fleas, live inside their host. They are worm-like organisms that live and feed off living hosts, receiving nourishment and protection while disrupting their hosts' nutrient...
Plagiorchis elegans, the larvae of parasitic flies, the feather mite
Feather mite
Feather mites are the members of diverse mite superfamilies:* superorder Acariformes** Psoroptidia*** Analgoidea*** Freyanoidea*** Pterolichoidea* superorder Parasitiformes** DermanyssoideaThey are ectoparasites on birds, hence the common name....
Metanalges elongatus, and hard ticks
Ixodidae
Ixodidae is a family of ticks containing the hard ticks.-Description:They are distinguished from the other main family of ticks, the soft ticks by the presence of a scutum or hard shield...
of the genera Haemaphysalis
Haemaphysalis
Haemaphysalis is a genus of tick.-Species:* Haemaphysalis aborensis Warburton, 1913* Haemaphysalis aciculifer Warburton 1913* Haemaphysalis aculeata Lavarra, 1904* Haemaphysalis adleri Feldman-Muhsam, 1951...
and Ixodes
Ixodes
Ixodes is a genus of hard-bodied ticks . It includes important disease vectors of animals and humans . Some ticks in this genus may transmit the pathogenic bacterium Borrelia burgdorferi responsible for causing Lyme disease...
. During the reintroduction of Corn Crakes to England in the 2003 breeding season, enteritis
Enteritis
In medicine, enteritis, from Greek words enteron and suffix -itis , refers to inflammation of the small intestine. It is most commonly caused by the ingestion of substances contaminated with pathogenic microorganisms. Symptoms include abdominal pain, cramping, diarrhea, dehydration and fever...
and ill heath in pre-release birds was due to bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
of a pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
ic Campylobacter
Campylobacter
Campylobacter is a genus of bacteria that are Gram-negative, spiral, and microaerophilic. Motile, with either unipolar or bipolar flagella, the organisms have a characteristic spiral/corkscrew appearance and are oxidase-positive. Campylobacter jejuni is now recognized as one of the main causes...
species. Subsequently, microbiology
Microbiology
Microbiology is the study of microorganisms, which are defined as any microscopic organism that comprises either a single cell , cell clusters or no cell at all . This includes eukaryotes, such as fungi and protists, and prokaryotes...
tests were done to detect infected individuals and to find the source of the bacteria in their environment.
Status
Both Crex species have huge breeding ranges, estimated at 15,700,000 km2 (4,500,000 mi2) for the African Crake and 12,400,000 km2 (4,800,000 mi2) for the Corn Crake. The population size of the African species is unknown, but it is common in most of its range, and its numbers appear to be stable. The European bird has an estimated 1.3–2.0 million breeding pairs in Europe, three-quarters of which are in European Russia, and a further 515,000–1,240,000 pairs in Asiatic Russia; the total Eurasian population has been estimated at between 5.45 and 9.72 million individuals. Both species are classed as Least ConcernLeast Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
. The Corn Crake was formerly classified as Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
because of serious declines in Europe, but improved monitoring in Russia indicates that anticipated losses there have not occurred and numbers have remained stable or possibly increased in Russia and Kazakhstan. Although most rails in the Old World are covered by the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA), neither Crex species is listed, being too terrestrial to be classed as wetland species.
Overgrazing, agriculture and the loss of wetland and moist grassland have reduced the availability of suitable habitat for the African Crake in many areas, such as some parts of the southern KwaZulu-Natal coast which have been urbanised or planted with sugarcane. In other areas, grassland may have increased locally in recent years as woodland is cleared. This crake is considered to be good eating, and is killed for food in some regions. Despite these adverse factors, it appears to be under no real threat.
In much of the western half of the Corn Crake's breeding range, there have been long-term declines that are expected to continue, although conservation measures have enabled numbers to grow in several countries, including substantial increases in the small populations in Finland, the UK and the Netherlands. The breeding population had begun to decline in the 19th century, but the process gained pace after World War II.Koffijberg & Schaffer (2006) p. 6 The main cause of the steep declines in much of Europe is the loss of nests and chicks from early mowing. Haymaking dates have moved forward in the past century due to faster crop growth, made possible by land drainage and the use of fertilisers, and the move from manual grass-cutting using scythes to mechanical mowers, at first horse-drawn and later pulled by tractors. Mechanisation also means that large areas can be cut quickly, leaving the crake with no alternative sites to raise either a first brood if suitable habitat has gone, or a replacement brood if the first nest is destroyed. The pattern of mowing, typically in a circular pattern from the outside of a field to its centre, gives little chance of escape for the chicks, which are also exposed to potential animal predators. Adults can often escape the mowers, although some incubating females sit tight on the nest, with fatal results.
Loss of habitat
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
is the other major threat to the Corn Crake, since drained and fertilised silage fields are less suitable for breeding than traditional hay meadows. In western Europe the conversion of grassland to arable land has been aided by subsidies, and further east the collapse of collective farming
Collective farming
Collective farming and communal farming are types of agricultural production in which the holdings of several farmers are run as a joint enterprise...
has led to the abandonment and lack of management of much land in this important breeding area. More localised threats include floods in spring, and disturbance by roads or wind farm
Wind farm
A wind farm is a group of wind turbines in the same location used to produce electric power. A large wind farm may consist of several hundred individual wind turbines, and cover an extended area of hundreds of square miles, but the land between the turbines may be used for agricultural or other...
s, and the loss of many birds – up to 14,000 a year – in Egypt, where migrating birds are captured in nets set for the quail with which they often migrate. Although this may account for 0.5–2.7% of the European population, the losses to this form of hunting are less than when the targeted species were more numerous and predictable.
Most European countries have taken steps to conserve the Corn Crake and produce national management policies; there is also an overall European action plan. The focus of conservation effort is to monitor populations and ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
and to improve survival, principally through changing the timing and method of hay harvesting. Later cutting gives time for breeding to be completed, and leaving uncut strips at the edges of fields and cutting from the centre outwards reduces the casualties from mowing. Implementing these changes is predicted to stop the population decline if the measures are applied on a sufficiently large scale. Reduction of illegal hunting, and protection in countries where hunting is still allowed, are also conservation aims. Reintroduction of the Corn Crake is being attempted in England, and breeding sites are scheduled for protection in many other countries. Where breeding sites impinge on urban areas, there are cost implications, estimated in one German study at several million euros per Corn Crake. The Corn Crake does not appear to be seriously threatened on its wintering grounds and may benefit from deforestration, which creates more open habitats.
Crex is a small genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s in the rail family
Rallidae
The rails, or Rallidae, are a large cosmopolitan family of small to medium-sized birds. The family exhibits considerable diversity and the family also includes the crakes, coots, and gallinules...
. It contains two species, the Corn Crake
Corn Crake
The Corn Crake, Corncrake or Landrail is a bird in the rail family. It breeds in Europe and Asia as far east as western China, and migrates to Africa for the winter...
, C. crex, which breeds across Europe and Asia and winters in southern Africa, and the African Crake
African Crake
The African Crake is a bird in the rail family that breeds in most of sub-Saharan Africa away from the arid south and southwest. It is seasonally common in most of its range other than the rainforests and areas that have low annual rainfall...
, C. egregia, which migrates
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
within Africa. Both are short-billed rails with blackish-brown upperparts, mainly blue-grey underparts, and barring on the flanks. The Corn Crake is significantly larger than its relative, and has a distinctive chestnut
Chestnut (color)
Chestnut, also known as Indian red, is a color, a medium brownish shade of red, and is named after the nut of the chestnut tree.As Indian red, it is named after the red laterite soil found in India. It is thus an earth tone as well as a red. It is composed of naturally occurring iron oxides. Other...
patch on its wings. Unusually for their family, these are birds of dry habitats rather than wetlands; the Eurasian species mainly breeds in hay meadows, and the African Crake in dry grassland. The African Crake is sometimes given its own genus, Crecopsis, but is now more usually placed in Crex.
Both species have distinctive loud grating calls used for advertising and territorial purposes in the breeding season, although the Corn Crake is silent on its African wintering grounds. They are mainly active during the day; they walk with a high-stepping action, and when disturbed they can run swiftly through grass or fly a short distance to cover. Migration takes place at night, and the ability to undertake these journeys is innate, not learned from adults. The nest is a shallow cup of grass lined with finer vegetation and built in a well hidden depression. The precocial
Precocial
In biology, the term precocial refers to species in which the young are relatively mature and mobile from the moment of birth or hatching. The opposite developmental strategy is called "altricial," where the young are born or hatched helpless. Extremely precocial species may be called...
chicks leave the nest soon after hatching, and fledge
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...
after four to six weeks. These are ground-feeding omnivore
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...
s, but mainly eat invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s. They may be killed by a variety of mammals and large birds, and infected by parasites.
The two Crex species have huge breeding ranges and large populations and are classed as Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
. The Corn Crake was formerly classified as Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
because of serious declines in western Europe, but improved monitoring shows that numbers have remained stable further east in Russia and Kazakhstan. In much of the western half of the Corn Crake's breeding range, there have been long-term declines that are expected to continue. The main cause of the decline is the loss of nests and chicks from early mowing. Haymaking dates have moved forward in the past century due to faster crop growth, made possible by land drainage and the use of fertilisers, and the move from manual grass-cutting using scythe
Scythe
A scythe is an agricultural hand tool for mowing grass, or reaping crops. It was largely replaced by horse-drawn and then tractor machinery, but is still used in some areas of Europe and Asia. The Grim Reaper is often depicted carrying or wielding a scythe...
s to mechanical mower
Mower
A mower is a machine for cutting grass or other plants that grow on the ground. Usually mowing is distinguished from reaping, which uses similar implements, but is the traditional term for harvesting grain crops, e.g...
s. Loss of habitat
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
is the other major threat to the Corn Crake. Drained and fertilised silage fields are less suitable for breeding than traditional hay meadows. In western Europe the conversion of grassland to arable land has been aided by subsidies, and further east the collapse of collective farming
Collective farming
Collective farming and communal farming are types of agricultural production in which the holdings of several farmers are run as a joint enterprise...
has led to the abandonment and lack of management of much land in this important breeding area.
Taxonomy
The railsRallidae
The rails, or Rallidae, are a large cosmopolitan family of small to medium-sized birds. The family exhibits considerable diversity and the family also includes the crakes, coots, and gallinules...
are a bird family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
comprising nearly 150 species. Although the origins of the group are lost in antiquity, the largest number of species and the most primitive forms are found in the Old World
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....
, suggesting that this family originated there. The genus Crex was created by German naturalist and ornithologist Johann Matthäus Bechstein
Johann Matthäus Bechstein
Johann Matthäus Bechstein was a German naturalist, forester, ornithologist and entomologist. In Great Britain, he was known for his treatise on singing birds .-Biography:Bechstein was born in Waltershausen in the district of Gotha in Thuringia...
in 1803. Originally it held only the Corn Crake, C. crex, which Bechstein moved from its original name, Rallus crex, given to it by Linnaeus in his Systema Naturae
Systema Naturae
The book was one of the major works of the Swedish botanist, zoologist and physician Carolus Linnaeus. The first edition was published in 1735...
in 1758. The taxonomy of the small crakes is complicated, but the closest relative of the Corn Crake is the African Crake, C. egregia. This was first described as Ortygometra egregria by Wilhelm Peters
Wilhelm Peters
Wilhelm Karl Hartwich Peters was a German naturalist and explorer.He was assistant to Johannes Peter Müller and later curator of the Berlin Zoological Museum. In September 1842 he travelled to Mozambique via Angola. He returned to Berlin with an enormous collection of natural history specimens...
in 1854 from a specimen obtained in Mozambique, and has variously been placed in the genus Porzana
Porzana
Porzana is a genus of birds in the crake or rail family, Rallidae. It has a global distribution, contains 13 living species, and 4-5 recently extinct ones...
or its own genus, Crecopsis, but is now more usually placed in Crex.Taylor & van Perlo (2000) p. 30Livezey (1998) p. 2098 The Porzana
Porzana
Porzana is a genus of birds in the crake or rail family, Rallidae. It has a global distribution, contains 13 living species, and 4-5 recently extinct ones...
crakes are the closest relatives of the Crex genus, particularly the Ash-throated Crake
Ash-throated Crake
The Ash-throated Crake is a species of bird in the Rallidae family.It is found in Argentina, Bolivia, Brazil, Colombia, French Guiana, Guyana, Paraguay, Peru, Suriname, Trinidad and Tobago, and Venezuela....
, Porzana albicollis, which has occasionally also been allocated to Crex.Livezey (1998) p. 2134
The genus name is onomatopoeic, referring to the repetitive grating call of the Corn Crake. Although these species occur in fairly open habitats, they lack the pure white undertail used for signalling in open water or gregarious species like the coot
Coot
Coots are medium-sized water birds that are members of the rail family Rallidae. They constitute the genus Fulica. Coots have predominantly black plumage, and, unlike many of the rails, they are usually easy to see, often swimming in open water...
s and moorhen
Moorhen
Moorhens, sometimes called marsh hens, are medium-sized water birds that are members of the rail family Rallidae. They constitute the genus Gallinula....
s.
Description
Sympatry
In biology, two species or populations are considered sympatric when they exist in the same geographic area and thus regularly encounter one another. An initially-interbreeding population that splits into two or more distinct species sharing a common range exemplifies sympatric speciation...
with the African Crake on its wintering grounds, but can be distinguished by its larger size, paler upperparts, chestnut-coloured patch on the upperwing and different underparts pattern. In flight, it has longer, less rounded wings, and shallower wingbeats than its African relative, and shows a white leading edge to the inner wing.
The sexes of each species are similar in appearance, although the females are slightly smaller and duller than the males, with a less contrasting head pattern. Juveniles of both species are duller than the adults, and browner underneath. Adults undergo a complete moult after breeding. No subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
have been recognised of either Crex crake. Although Corn Crakes become paler and greyer towards the east of the range, the change is clinal, and there is great individual variation in colour within all populations.
The two Crex crakes are unlikely to be confused with other rails, since most sympatric short-billed rails are smaller, with white markings on the upperparts, different underparts patterns and shorter bills. The European Water Rail
Water Rail
The Water Rail is a bird of the rail family which breeds in well-vegetated wetlands across Europe, Asia and North Africa. Northern and eastern populations are migratory, but this species is a permanent resident in the warmer parts of its breeding range...
and the African Rail
African Rail
The African Rail is a small wetland bird of the rail family.Its breeding habitat is marshes and reedbeds across eastern and southern Africa from Ethiopia to South Africa...
have long pointed bills.
Voice
Like other rails, the Crex species have a wide range of vocalisations. The males of both crakes have a loud territorial and advertising call consisting of a series of grating notes repeated two or three times a second for several minutes. The male stands upright with his neck extended when advertising, with its head and neck almost vertical and bill wide open. Calling is most frequent early in the breeding season, mainly at night for the Corn Crake, but in the day for its African cousin. The Corn Crake's call may be repeated more than 20,000 times a night, with a peak between midnight and 3 am.The advertising calls of both crakes are readily distinguished from the quite dissimilar calls of potentially sympatric
Sympatry
In biology, two species or populations are considered sympatric when they exist in the same geographic area and thus regularly encounter one another. An initially-interbreeding population that splits into two or more distinct species sharing a common range exemplifies sympatric speciation...
rails such as the Spotted Crake
Spotted Crake
The Spotted Crake is a small waterbird, of the family Rallidae.Their breeding habitat is marshes and sedge beds across temperate Europe into western Asia. They nest in a dry location in marsh vegetation, laying 6-15 eggs...
, Striped Crake
Striped Crake
The Striped Crake is a species of bird in the Rallidae family. It is the only species in the genus Aenigmatolimnas....
, Baillon's Crake
Baillon's Crake
The Baillon's Crake is a very small waterbird of the family Rallidae.-Distribution:Their breeding habitat is sedge beds in Europe, mainly in the east, and across Asia. They used to breed in Great Britain up to the mid-19th century, but the western European population declined through drainage....
, or Water Rail
Water Rail
The Water Rail is a bird of the rail family which breeds in well-vegetated wetlands across Europe, Asia and North Africa. Northern and eastern populations are migratory, but this species is a permanent resident in the warmer parts of its breeding range...
.Taylor & van Perlo (2000) pp. 293–299 The calls of the two Crex species cannot be confused, since the Corn Crake is silent in Africa. Both sexes may give distinctive territorial or alarm calls, and females and chicks communicate with cheeps and wheezes. The African Crake can be attracted to within 10 m (30 ft) of a human by imitation of its kraaa threat call, and the male Corn Crake by mechanical imitations of their advertising call, including rubbing a piece of wood down a notched stick, or by flicking a credit card against a comb or zip-fastener
Zipper
A zipper is a commonly used device for temporarily joining two edges of fabric...
.
Distribution and habitat
The Corn Crake is a long distance migrant, breeding across temperate Eurasia from the British IslesBritish Isles
The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...
east to central Siberia and western China. It winters in Africa from Zaire and central Tanzania south to eastern South Africa, mainly KwaZulu-Natal
KwaZulu-Natal
KwaZulu-Natal is a province of South Africa. Prior to 1994, the territory now known as KwaZulu-Natal was made up of the province of Natal and the homeland of KwaZulu....
and the former Transvaal Province
Transvaal Province
Transvaal Province was a province of the Union of South Africa from 1910 to 1961, and of its successor, the Republic of South Africa, from 1961 until the end of apartheid in 1994 when a new constitution subdivided it.-History:...
. Small numbers of birds may winter in the milder areas of western Europe, or halt their migration and stay in North Africa
North Africa
North Africa or Northern Africa is the northernmost region of the African continent, linked by the Sahara to Sub-Saharan Africa. Geopolitically, the United Nations definition of Northern Africa includes eight countries or territories; Algeria, Egypt, Libya, Morocco, South Sudan, Sudan, Tunisia, and...
.
The African Crake occurs throughout sub-Saharan Africa from Senegal east to Kenya and south to KwaZulu-Natal, except in arid areas of south and southwest Africa where the annual summer rainfall is less than 300 mm (11.8 in). It is widespread and locally common in most of its range, apart from the rainforest
Rainforest
Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...
s and the drier regions. Nearly all the South African population of about 8,000 birds occur in KwaZulu-Natal and the former Transvaal Province. This crake is only a vagrant
Vagrancy (biology)
Vagrancy is a phenomenon in biology whereby individual animals appear well outside their normal range; individual animals which exhibit vagrancy are known as vagrants. The term accidental is sometimes also used...
to the drier zones on the southern edges of South Africa's northern and eastern Cape Province
Cape Province
The Province of the Cape of Good Hope was a province in the Union of South Africa and subsequently the Republic of South Africa...
and North West Province
North West (South African province)
North West is a province of South Africa. Its capital is Mafikeng. The province is located to the west of the major population centre of Gauteng.-History:...
, and southern Botswana. Retrieved 26 May 2011
Both species are nocturnal migrants. Most Corn Crakes migrate through Egypt, with smaller numbers crossing at the western end of the Mediterranean
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
. It has been recorded in most countries between its breeding and wintering ranges, including much of west Africa, and those parts of southern Asia that lie between the east of the breeding range and Africa. Further afield, it has been recorded as a vagrant to Sri Lanka, Vietnam and Australia,Bräunlich, Axel; Rank, Michael (2001)Notes on the occurrence of the Corncrake (Crex crex) in Asia and in the Pacific region pp. 10–13 in Schäffer, N; Mammen, U (eds.) (2001) Proceedings International Corncrake Workshop 1998, Hilpoltstein/Germany. the Seychelles, Bermuda, Canada, the United States, Greenland, and the North Atlantic islands.
The African species is a partial migrant
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
, but its movements are complex, seasonal and poorly studied. It is mainly a wet-season breeder, and many birds move away from the equator as soon as the rains provide sufficient grass cover to allow them to breed elsewhere. Southward movement is mainly from November to April, the return north beginning when burning or drought reduces the grass cover again. This species is present throughout the year in some West African countries, and in equatorial regions, but even in those areas numbers vary seasonally due to local movements; internal north–south migration has been noted within countries including Nigeria, Senegal, The Gambia, Ivory Coast and Cameroon. This crake has also wandered further afield. It is rare on Bioko Island
Bioko
Bioko is an island 32 km off the west coast of Africa, specifically Cameroon, in the Gulf of Guinea. It is the northernmost part of Equatorial Guinea with a population of 124,000 and an area of . It is volcanic with its highest peak the Pico Basile at .-Geography:Bioko has a total area of...
(Equatorial Guinea),Larison, Brenda; Smith, Thomas B; Milá, Borja; Stauffer, Donald; Nguema, José (1999) " Bird and Mammal Surveys of Rio Muni" pp. 9–57 in and there have been two records each for São Tomé
São Tomé Island
São Tomé Island, at , is the largest island of São Tomé and Príncipe and is home in 2009 to about 157,000 or 96% of the nation's population. This island and smaller nearby islets make up São Tomé Province, which is divided into six districts. The main island is located 2 km north of the...
and Tenerife
Tenerife
Tenerife is the largest and most populous island of the seven Canary Islands, it is also the most populated island of Spain, with a land area of 2,034.38 km² and 906,854 inhabitants, 43% of the total population of the Canary Islands. About five million tourists visit Tenerife each year, the...
, the Canary Islands
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
birds being the first records for the Western Palaeartic.
Most rails are wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....
birds, but the two Crex species prefer drier habitats. The African Crake is found mainly in grassland, ranging from wetland edges and seasonal floodlands to savanna
Savanna
A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.Some...
, lightly wooded dry grassland, and grassy forest clearings. It also frequents maize, rice and cotton crops, derelict farmland and sugarcane plantations close to water. A wide range of grass species are used, with a preferred height of 0.3–1 m (1–3 ft) tall but vegetation is acceptable up to 2 m (6 ft) tall. The Corn Crake is mainly a lowland species, but breeds up to 1,400 m (4,600 ft) altitude in the Alps
Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....
, 2,700 m (8,600 ft) in China and 3,000 m (9,800 ft) in Russia. When breeding in Eurasia, the Corn Crake's habitats would originally have included river meadows with tall grass and meadow plants, but it is now mainly found in cool moist grassland used for the production of hay, particularly moist traditional farmland. It also utilises other treeless grasslands in mountains or taiga
Taiga
Taiga , also known as the boreal forest, is a biome characterized by coniferous forests.Taiga is the world's largest terrestrial biome. In North America it covers most of inland Canada and Alaska as well as parts of the extreme northern continental United States and is known as the Northwoods...
, on coasts, or where created by fire. Very wet habitats are avoided, as are open areas and those with vegetation more than 50 cm (20 in) tall, or too dense for the birds to walk through.
While wintering in Africa, the Corn Crake occupies dry grassland and savanna habitats, occurring in vegetation 30–200 cm (1–6 ft) tall, including seasonally burnt areas and occasionally sedges or reed bed
Reed bed
Reed beds are natural habitats found in floodplains, waterlogged depressions andestuaries. Reed beds are part of a succession from young reed colonising open water or wet ground through a gradation of increasingly dry ground...
s. It is also found on fallow and abandoned fields, uncut grass on airfields, and the edges of crops. It occurs at up to at least 1,750 m (5,700 ft) altitude in South Africa. Although it sometimes occurs with the African Crake, that species normally prefers moister and shorter grassland habitats than does the Corn Crake. On migration, the Corn Crake may also occur in wheatfields and around golf course
Golf course
A golf course comprises a series of holes, each consisting of a teeing ground, fairway, rough and other hazards, and a green with a flagstick and cup, all designed for the game of golf. A standard round of golf consists of playing 18 holes, thus most golf courses have this number of holes...
s.
Behaviour
Both Crex crakes are mainly active during the day, especially at dawn, dusk, during light rain, or after heavier rain. The African Crake is less skulking and easier to flush from cover than other crakes, and is often seen at the edges of roads and tracks, but the Corn Crake is a much more difficult bird to see in its breeding sites, usually being hidden by vegetation and rarely emerging into the open. Both crakes are territorial on both the breeding and non-breeding grounds; the male threat displays involves the bird standing upright and spreading the feathers of the wings, flanks and belly like a fan. Fighting at territorial boundaries involves the male birds jumping at each other and pecking.Both species walk with a high-stepping action, and can run swiftly through grass with the body held horizontal and laterally flattened. When disturbed, they typically fly less than 50 m (150 ft), frequently landing behind a bush or thicket, and then go into a crouch. In short grass, they can escape from a dog using their speed and maneuverability, running with the body held almost horizontal. The typical flight is weak and fluttering, especially that of the African Crake, but for longer flights, such as migration, the Corn Crake has a steadier, stronger action with its legs drawn up. Flocks of up to 40 Corn Crakes may form on migration, sometimes associating with Common Quail
Common Quail
The Common Quail, Coturnix coturnix, is a small bird in the pheasant family Phasianidae. It is widespread and is found in parts of Europe, .- Description :It is a small rotund bird, essentially streaked brown with...
s. Migration takes place at night, and flocks resting during the day may aggregate to hundreds of birds at favoured sites. The ability to migrate is innate, not learned from adults; chicks raised from birds kept in captivity for ten generations were able to migrate to Africa and return with similar success to wild-bred young.
Breeding
Both crakes were formerly believed to be monogamousMonogamy
Monogamy /Gr. μονός+γάμος - one+marriage/ a form of marriage in which an individual has only one spouse at any one time. In current usage monogamy often refers to having one sexual partner irrespective of marriage or reproduction...
, but the male Corn Crake may have a shifting home range, and mate with two or more females, moving on when laying is almost complete. The breeding display consists of a short chase of the female by the male. The nest is a shallow cup of grass leaves and lined with finer grasses, built in a depression and well hidden in the grass. The clutch
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...
size is from 3 to 11 pink eggs for the African species, and 6–14 – usually 8–12 – for the European breeder. The Corn Crake's eggs are oval, slightly glossy, creamy or tinted with green, blue or grey, and blotched red-brown. They average 37 × 26 mm, (1.5 × 1.0 in) and weigh about 13–16 g, (0.46–0.56 oz), of which 7% is shell.
The first egg is often laid when the nest is little more than a pad of grass, and a further egg is laid on each subsequent day. Both sexes incubate the eggs, which start hatching after about 14 days; all hatch with 48 hours despite the extended laying period. The black, downy precocial
Precocial
In biology, the term precocial refers to species in which the young are relatively mature and mobile from the moment of birth or hatching. The opposite developmental strategy is called "altricial," where the young are born or hatched helpless. Extremely precocial species may be called...
chicks soon leave the nest but are fed and protected by the parents. Fledging
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...
occurs after four to six weeks, and the young can fly before they are fully grown. It is not known whether the African Crake has a second brood, but the Corn Crake usually does. Where grass is not tall enough at the start of the season, the first nest may be constructed in herby or marsh vegetation, with the second brood in hay. The second nest may also be at a higher altitude that the first, to take advantage of the later-developing grasses further up a hill.
Although survival in undisturbed sites is high, at 80–90%, the Corn Crake suffers from modern farming practices, since mechanised mowing can kill 38–95% of chicks in a given site. The influence of weather on Corn Crake chick survival is limited: although chick growth is faster in dry or warm weather, the effects are relatively small. Unlike many precocial species, chicks are fed by their mother for a few days until they become independent, and this may cushion them from adverse conditions. The number of live chicks hatched is more important than the weather, with lower survival in large broods.
Feeding
Both Crex crakes are omnivorousOmnivore
Omnivores are species that eat both plants and animals as their primary food source...
, but mainly feed on invertebrates, including earthworm
Earthworm
Earthworm is the common name for the largest members of Oligochaeta in the phylum Annelida. In classical systems they were placed in the order Opisthopora, on the basis of the male pores opening posterior to the female pores, even though the internal male segments are anterior to the female...
s, slug
Slug
Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...
s and snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
s, spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
s, beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s, dragonflies
Dragonfly
A dragonfly is a winged insect belonging to the order Odonata, the suborder Epiprocta or, in the strict sense, the infraorder Anisoptera . It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body...
, grasshopper
Grasshopper
The grasshopper is an insect of the suborder Caelifera in the order Orthoptera. To distinguish it from bush crickets or katydids, it is sometimes referred to as the short-horned grasshopper...
s and other insects. The Corn Crake may take pests such as Sitona
Sitona
Sitona is a large genus of weevils in the family Curculionidae, native to the Nearctic and Palaearctic regions. More than 100 species have been described...
weevil
Weevil
A weevil is any beetle from the Curculionoidea superfamily. They are usually small, less than , and herbivorous. There are over 60,000 species in several families, mostly in the family Curculionidae...
s, leatherjacket
Crane fly
A crane fly is an insect in the family Tipulidae. Adults are very slender, long-legged flies that may vary in length from though tropical species may exceed to ....
s and wireworm
Click beetle
The family Elateridae is commonly called click beetles , elaters, snapping beetles, spring beetles or "skipjacks". They are a cosmopolitan beetle family characterized by the unusual click mechanism they possess...
s. In Africa, termite
Termite
Termites are a group of eusocial insects that, until recently, were classified at the taxonomic rank of order Isoptera , but are now accepted as the epifamily Termitoidae, of the cockroach order Blattodea...
s, cockroach
Cockroach
Cockroaches are insects of the order Blattaria or Blattodea, of which about 30 species out of 4,500 total are associated with human habitations...
es and dung beetle
Dung beetle
Dung beetles are beetles that feed partly or exclusively on feces. All of these species belong to the superfamily Scarabaeoidea; most of them to the subfamilies Scarabaeinae and Aphodiinae of the family Scarabaeidae. This beetle can also be referred to as the scarab beetle. As most species of...
s may be consumed. These opportunist hunters will take the occasional vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
such as a small frog, rodent or fish. Food is taken from the ground, low-growing plants and from inside grass tussocks; the crake may search leaf litter with its bill, and run in pursuit of active prey. In Africa, both species will occasionally feed on grassy tracks or dirt roads. Plant material is eaten, especially grass seeds, but also green shoots, leaves and other seeds. As with other rails, grit is swallowed to help break up food in the stomach. Indigestible material is regurgitated as pellets
Pellet (ornithology)
A pellet, in ornithology, is the mass of undigested parts of a bird's food that some bird species occasionally regurgitate. The contents of a bird's pellet depend on its diet, but can include the exoskeletons of insects, indigestible plant matter, bones, fur, feathers, bills, claws, and teeth...
. Chicks are fed mainly on animal food. Crex crakes forage singly, in pairs or in family groups, sometimes in association with the other member of the genus or with other grassland birds such as Great Snipe
Great Snipe
The Great Snipe, Gallinago media is a small stocky wader in the genus Gallinago.This bird's breeding habitat is marshes and wet meadows with short vegetation in north-eastern Europe including north-western Russia. Great Snipes are migratory, wintering in Africa...
s, Blue Quail
Blue Quail
The Blue Quail or African Blue Quail, is a species of bird in the Phasianidae family.-Geographic Range:The species ranges from Sierra Leone to Ethiopia, and south to Zambia, and eastward to Kenya, and is migratory...
s and Common Quails.
Predators and parasites
Predators of the Corn Crake on its European breeding grounds include feralFeral
A feral organism is one that has changed from being domesticated to being wild or untamed. In the case of plants it is a movement from cultivated to uncultivated or controlled to volunteer. The introduction of feral animals or plants to their non-native regions, like any introduced species, may...
and domestic cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s, introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
American Mink
American Mink
The American mink is a semi-aquatic species of Mustelid native to North America, though human intervention has expanded its range to many parts of Europe and South America. Because of this, it is classed as Least Concern by the IUCN. Since the extinction of the sea mink, the American mink is the...
, feral Ferret
Ferret
The ferret is a domesticated mammal of the type Mustela putorius furo. Ferrets are sexually dimorphic predators with males being substantially larger than females. They typically have brown, black, white, or mixed fur...
s, Otters
European Otter
The European Otter , also known as the Eurasian otter, Eurasian river otter, common otter and Old World otter, is a European and Asian member of the Lutrinae or otter subfamily, and is typical of freshwater otters....
and Red Foxes
Red Fox
The red fox is the largest of the true foxes, as well as being the most geographically spread member of the Carnivora, being distributed across the entire northern hemisphere from the Arctic Circle to North Africa, Central America, and the steppes of Asia...
, and birds including the Common Buzzard
Common Buzzard
The Common Buzzard is a medium to large bird of prey, whose range covers most of Europe and extends into Asia. It is usually resident all year, except in the coldest parts of its range, and in the case of one subspecies.-Description:...
and Hooded Crow
Hooded Crow
The Hooded Crow is a Eurasian bird species in the crow genus. Widely distributed, it is also known locally as Scotch Crow, Danish Crow, and Corbie or Grey Crow in Ireland, which is what its Welsh name, Brân Lwyd, translates as...
. In Lithuania, the introduced Raccoon Dog
Raccoon Dog
The raccoon dog , also known as the magnut or tanuki, is a canid indigenous to east Asia. It is the only extant species in the genus Nyctereutes...
has also been recorded taking Corn Crakes. When chicks are exposed by rapid mowing, they may be taken by large birds including the White Stork
White Stork
The White Stork is a large bird in the stork family Ciconiidae. Its plumage is mainly white, with black on its wings. Adults have long red legs and long pointed red beaks, and measure on average from beak tip to end of tail, with a wingspan...
, harriers
Harrier (bird)
A harrier is any of the several species of diurnal hawks forming the Circinae sub-family of the Accipitridae family of birds of prey. Harriers characteristically hunt by flying low over open ground, feeding on small mammals, reptiles, or birds....
and other birds of prey
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
, gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s and corvids
Corvidae
Corvidae is a cosmopolitan family of oscine passerine birds that contains the crows, ravens, rooks, jackdaws, jays, magpies, treepies, choughs and nutcrackers. The common English names used are corvids or the crow family , and there are over 120 species...
.Koffijberg & Schaffer (2006) p. 21 At undisturbed sites, nests and broods are rarely attacked, which is reflected in the high breeding success.
In Africa, Crex species may be hunted by the Leopard
Leopard
The leopard , Panthera pardus, is a member of the Felidae family and the smallest of the four "big cats" in the genus Panthera, the other three being the tiger, lion, and jaguar. The leopard was once distributed across eastern and southern Asia and Africa, from Siberia to South Africa, but its...
, Serval
Serval
The serval , Leptailurus serval or Caracal serval, known in Afrikaans as Tierboskat, "tiger-forest-cat", is a medium-sized African wild cat. DNA studies have shown that the serval is closely related to the African golden cat and the caracal...
, cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s, the Black-headed Heron
Black-headed Heron
The Black-headed Heron is a wading bird of the heron family Ardeidae, common throughout much of sub-Saharan Africa and Madagascar. It is mainly resident but some west African birds move further north in the rainy season....
, Dark Chanting Goshawk
Dark Chanting Goshawk
The Dark Chanting Goshawk is a bird of prey in the family Accipitridae. The Accipitridae also include many other diurnal raptors such as kites, eagles and harriers....
, African Hawk-Eagle, Wahlberg's Eagle
Wahlberg's Eagle
The Wahlberg's Eagle is a bird of prey. It is about 55–60 cm in length and has a wingspan of 130–160 cm. Body mass is 1.04 kg for males and 1.3 kg for females on average. Like all eagles, it belongs to the family Accipitridae.Wahlberg's Eagle breeds in most of Africa south of...
,Taylor & van Perlo (2000) pp. 316–320 and Black Sparrowhawk.Taylor & van Perlo (2000) pp. 320–327 In South Africa, newly hatched African Crake chicks were taken by a Boomslang
Boomslang
The boomslang is a large venomous colubrid snake.-Taxonomy & etymology:It is currently the only species in its genus, although several species and subspecies have been described in the past...
.
Parasites recorded in this genus include the widespread fluke
Trematoda
Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:...
Prosthogonimus ovatus( which lives in the oviduct
Oviduct
In non-mammalian vertebrates, the passageway from the ovaries to the outside of the body is known as the oviduct. The eggs travel along the oviduct. These eggs will either be fertilized by sperm to become a zygote, or will degenerate in the body...
s of birds), the parasitic worm
Parasitic worm
Parasitic worms or helminths are a division of eukaryoticparasites that, unlike external parasites such as lice and fleas, live inside their host. They are worm-like organisms that live and feed off living hosts, receiving nourishment and protection while disrupting their hosts' nutrient...
Plagiorchis elegans, the larvae of parasitic flies, the feather mite
Feather mite
Feather mites are the members of diverse mite superfamilies:* superorder Acariformes** Psoroptidia*** Analgoidea*** Freyanoidea*** Pterolichoidea* superorder Parasitiformes** DermanyssoideaThey are ectoparasites on birds, hence the common name....
Metanalges elongatus, and hard ticks
Ixodidae
Ixodidae is a family of ticks containing the hard ticks.-Description:They are distinguished from the other main family of ticks, the soft ticks by the presence of a scutum or hard shield...
of the genera Haemaphysalis
Haemaphysalis
Haemaphysalis is a genus of tick.-Species:* Haemaphysalis aborensis Warburton, 1913* Haemaphysalis aciculifer Warburton 1913* Haemaphysalis aculeata Lavarra, 1904* Haemaphysalis adleri Feldman-Muhsam, 1951...
and Ixodes
Ixodes
Ixodes is a genus of hard-bodied ticks . It includes important disease vectors of animals and humans . Some ticks in this genus may transmit the pathogenic bacterium Borrelia burgdorferi responsible for causing Lyme disease...
. During the reintroduction of Corn Crakes to England in the 2003 breeding season, enteritis
Enteritis
In medicine, enteritis, from Greek words enteron and suffix -itis , refers to inflammation of the small intestine. It is most commonly caused by the ingestion of substances contaminated with pathogenic microorganisms. Symptoms include abdominal pain, cramping, diarrhea, dehydration and fever...
and ill heath in pre-release birds was due to bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
of a pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
ic Campylobacter
Campylobacter
Campylobacter is a genus of bacteria that are Gram-negative, spiral, and microaerophilic. Motile, with either unipolar or bipolar flagella, the organisms have a characteristic spiral/corkscrew appearance and are oxidase-positive. Campylobacter jejuni is now recognized as one of the main causes...
species. Subsequently, microbiology
Microbiology
Microbiology is the study of microorganisms, which are defined as any microscopic organism that comprises either a single cell , cell clusters or no cell at all . This includes eukaryotes, such as fungi and protists, and prokaryotes...
tests were done to detect infected individuals and to find the source of the bacteria in their environment.
Status
Both Crex species have huge breeding ranges, estimated at 15,700,000 km2 (4,500,000 mi2) for the African Crake and 12,400,000 km2 (4,800,000 mi2) for the Corn Crake. The population size of the African species is unknown, but it is common in most of its range, and its numbers appear to be stable. The European bird has an estimated 1.3–2.0 million breeding pairs in Europe, three-quarters of which are in European Russia, and a further 515,000–1,240,000 pairs in Asiatic Russia; the total Eurasian population has been estimated at between 5.45 and 9.72 million individuals. Both species are classed as Least ConcernLeast Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
. The Corn Crake was formerly classified as Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
because of serious declines in Europe, but improved monitoring in Russia indicates that anticipated losses there have not occurred and numbers have remained stable or possibly increased in Russia and Kazakhstan. Although most rails in the Old World are covered by the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA), neither Crex species is listed, being too terrestrial to be classed as wetland species.
Overgrazing, agriculture and the loss of wetland and moist grassland have reduced the availability of suitable habitat for the African Crake in many areas, such as some parts of the southern KwaZulu-Natal coast which have been urbanised or planted with sugarcane. In other areas, grassland may have increased locally in recent years as woodland is cleared. This crake is considered to be good eating, and is killed for food in some regions. Despite these adverse factors, it appears to be under no real threat.
In much of the western half of the Corn Crake's breeding range, there have been long-term declines that are expected to continue, although conservation measures have enabled numbers to grow in several countries, including substantial increases in the small populations in Finland, the UK and the Netherlands. The breeding population had begun to decline in the 19th century, but the process gained pace after World War II.Koffijberg & Schaffer (2006) p. 6 The main cause of the steep declines in much of Europe is the loss of nests and chicks from early mowing. Haymaking dates have moved forward in the past century due to faster crop growth, made possible by land drainage and the use of fertilisers, and the move from manual grass-cutting using scythes to mechanical mowers, at first horse-drawn and later pulled by tractors. Mechanisation also means that large areas can be cut quickly, leaving the crake with no alternative sites to raise either a first brood if suitable habitat has gone, or a replacement brood if the first nest is destroyed. The pattern of mowing, typically in a circular pattern from the outside of a field to its centre, gives little chance of escape for the chicks, which are also exposed to potential animal predators. Adults can often escape the mowers, although some incubating females sit tight on the nest, with fatal results.
Loss of habitat
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
is the other major threat to the Corn Crake, since drained and fertilised silage fields are less suitable for breeding than traditional hay meadows. In western Europe the conversion of grassland to arable land has been aided by subsidies, and further east the collapse of collective farming
Collective farming
Collective farming and communal farming are types of agricultural production in which the holdings of several farmers are run as a joint enterprise...
has led to the abandonment and lack of management of much land in this important breeding area. More localised threats include floods in spring, and disturbance by roads or wind farm
Wind farm
A wind farm is a group of wind turbines in the same location used to produce electric power. A large wind farm may consist of several hundred individual wind turbines, and cover an extended area of hundreds of square miles, but the land between the turbines may be used for agricultural or other...
s, and the loss of many birds – up to 14,000 a year – in Egypt, where migrating birds are captured in nets set for the quail with which they often migrate. Although this may account for 0.5–2.7% of the European population, the losses to this form of hunting are less than when the targeted species were more numerous and predictable.
Most European countries have taken steps to conserve the Corn Crake and produce national management policies; there is also an overall European action plan. The focus of conservation effort is to monitor populations and ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
and to improve survival, principally through changing the timing and method of hay harvesting. Later cutting gives time for breeding to be completed, and leaving uncut strips at the edges of fields and cutting from the centre outwards reduces the casualties from mowing. Implementing these changes is predicted to stop the population decline if the measures are applied on a sufficiently large scale. Reduction of illegal hunting, and protection in countries where hunting is still allowed, are also conservation aims. Reintroduction of the Corn Crake is being attempted in England, and breeding sites are scheduled for protection in many other countries. Where breeding sites impinge on urban areas, there are cost implications, estimated in one German study at several million euros per Corn Crake. The Corn Crake does not appear to be seriously threatened on its wintering grounds and may benefit from deforestration, which creates more open habitats.