Heron
Encyclopedia
The herons are long-legged freshwater and coastal bird
s in the family Ardeidae. There are 64 recognised species
in this family. Some are called "egret
s" or "bittern
s" instead of "heron".
Within the family, all members of the genera Botaurus and Ixobrychus are referred to as "bitterns", and — including the Zigzag Heron
or Zigzag Bittern — are a monophyletic group within the Ardeidae. However, egrets are not a biologically distinct group from the herons, and tend to be named differently because they are mainly white and/or have decorative plumes. Although egrets have the same build as the larger herons, they tend to be smaller.
The classification of the individual heron/egret species is fraught with difficulty, and there is still no clear consensus about the correct placement of many species into either of the two major genera, Ardea
and Egretta
. Similarly, the relationship of the genera
in the family is not completely resolved. However, one species formerly considered to constitute a separate monotypic
family Cochlearidae, the Boat-billed Heron
, is now regarded as a member of the Ardeidae.
Although herons resemble birds in some other families, such as the stork
s, ibis
es and spoonbill
s, they differ from these in flying with their necks retracted, not outstretched. They are also one of the bird groups that have powder down.
Some members of this group nest colonially
in trees; others, notably the bitterns, use reedbeds.
in size. The smallest species is usually considered the Little Bittern
, although all the species in the Ixobrychus
genus are small and many broadly overlap in size. The largest species of heron is the Goliath Heron
. The necks are able to kink in an s-shape, due to the modified shape of the sixth vertebrae. The neck is able to retract and extend, and is retracted during flight, unlike most other long-necked birds. The neck is longer in the day herons than the night herons and bitterns. The legs are long and strong and in almost every species are unfeathered from the lower part of the tibia (the exception is the Zigzag Heron
). In flight the legs and feet are held backward. The feet of herons have long thin toes, with three forward pointing ones and one going backward.
The bill
is generally long and harpoon like. It can vary from extremely fine, as in the Agami Heron
, to thick as in the Grey Heron
. The most atypical bill is owned by the Boat-billed Heron
, which has a broad thick bill. The bill, as well as other bare parts of the body, is usually yellow, black or brown coloured, although this colour can vary during the breeding season. The feather
s of the herons are soft. The plumage
of the herons is usually blue, black, brown, grey or white, and can often be strikingly complex. Amongst the day herons there is little sexual dimorphism in plumage (except in the pond-herons); differences between the sexes are the rule for the night herons and smaller bitterns. Many species also have different colour morphs. In the Pacific Reef Heron there are both dark and light colour morphs, and the percentage of each morph varies geographically. White morphs only occur in areas with coral beaches.
. They exist on all continents except Antarctica, and are present in most habitats except the coldest extremes of the Arctic, extremely high mountains and the driest deserts. Almost all species are associated with water, they are essentially non-swimming waterbirds that feed on the margins of lakes, rivers, swamps, ponds and the sea. They are predominately found in lowland areas, although some species live in alpine areas, and the majority of species occur in the tropics.
The herons are a highly mobile family, with most species being at least partially migratory
. Some species are partially migratory, for example the Grey Heron
, which is mostly sedentary in Britain but mostly migratory in Scandinavia. Birds are particularly inclined to disperse widely after breeding but before the annual migration where the species is colonial, searching out new feeding areas and reducing the pressures on feeding grounds near the colony. The migration typically occurs at night, usually as individuals or in small groups.
, which specialises in crustaceans, particularly crabs. Many species will also opportunistically take larger prey, including birds and bird eggs, and more rarely carrion. Even more rarely there have been reports of herons eating acorns, peas and grains, but most vegetable matter consumed is accidental.
The most common hunting technique is for the bird to sit motionless on the edge of or standing in shallow water and wait until prey comes within range. Birds may either do this from an upright posture, giving them a wider field of view for seeing prey, or from a crouched position, which is more cryptic and means the bill is closer to the prey when it is located. Having seen prey the head is moved from side to side, so that the heron can calculate the position of the prey in the water and compensate for refraction
, and then the bill is used to spear the prey.
In addition to sitting and waiting, herons may feed more actively. They may walk slowly, at around or less than 60 paces a minute, snatching prey when it is observed. Other active feeding behaviours include foot stirring and probing, where the feet are used to flush out hidden prey. The wings may be used to frighten prey (or possibly attract it to shade) or to reduce glare; the most extreme example of this is exhibited by the Black Heron
, which forms a full canopy with its wings over its body.
Some species of heron , such as the Little Egret
and Grey Heron
, have been documented using bait in order to lure prey to within striking distance. Herons may use items already in place, or actively add items to the water in order to attract fish. Items used may be man made, such as bread; alternatively Striated Heron
s in the Amazon
have been watched repeatedly dropping seeds, insects, flowers and leaves into the water to catch fish.
Three species, the Black-headed Heron
, Whistling Heron
and especially the Cattle Egret
are less tied to watery environments and may feed far away from water. Cattle Egrets improve their foraging success by following large grazing animals, catching insects flushed by their movement. One study found that the success rate of prey capture increased 3.6 times over solitary foraging.
While the family exhibits a range of breeding strategies, overall the herons are monogamous
and mostly colonial
. Most day-herons and night-herons are colonial, or partly colonial depending on circumstances, whereas the bitterns and tiger-herons are mostly solitary nesters. Colonies may contain several species as well as other types of waterbird. In a study of Little Egrets and Cattle Egrets in India the majority of the colonies surveyed contained both species. Nesting is seasonal in temperate species; in tropical species it may be seasonal (often coinciding with the rainy season) or year-round. Even in year-round breeders nesting intensity varies throughout the year. Tropical herons typically have only one breeding season per year, unlike some other tropical birds which may raise up to three broods a year.
Courtship usually takes part on the nest
. Males arrive first and begin the building of the nest, where they display to attract females. In colonial species displays involve visual cues, which can include adopting postures or ritual displays, whereas in solitary species auditory cues, such as the deep booming of the bitterns, are important. The exception to this is the Boat-billed Heron, which pairs up away from the nesting site. Having paired the pair continue to build the nest in almost all species, although in the Little Bittern
and Least Bittern
only the male works on the nest.
Some ornithologists
have reported observing female herons attaching themselves to impotent
mates, then seeking sexual gratification elsewhere.
The nests of herons are usually found near or above water. They are typically placed in vegetation, although the nests of a few species have been found on the ground where suitable trees of shrubs are unavailable. Trees are used by many species, and here they may be placed high up from the ground, whereas species living in reedbeds may nest very close to the ground.
Generally herons lay between three to seven eggs
. Larger clutches are reported in the smaller bitterns and more rarely some of the larger day-herons, and single egg clutches are reported for some of the tiger-herons. Clutch size varies by latitude within species, with individuals in temperate climates laying more eggs than tropical ones. On the whole the eggs are glossy blue or white, with the exception being the large bitterns which lay olive-brown eggs.
suggests that herons were given this name because of their habit of defecating when flushed. The terms "shitepoke" or "shikepoke" can be used as insults in a number of situations. For example, the term "shikepoke" appears in the 1931 play Green Grow The Lilacs
, and in the 1943 musical play Oklahoma!
.
The 1971 Compact Edition of the Oxford English Dictionary describes the use of "shitepoke" for the small green heron of North America (Butorides virescens) as originating in the United States
, citing a published example from 1853. The OED also observes that "shiterow" or "shederow" are terms used for herons, and also applied as derogatory terms meaning a "thin weakly person". This name for a heron is found in a list of gamebirds in a royal decree of James VI (1566–1625) of Scotland
. The OED speculates that "shiterow" is a corruption of "shiteheron".
, suggested that the Ardeidae could be split into a diurnal
and a crepuscular
/nocturnal group which included the bitterns. From DNA
studies and skeletal analyses focusing more on bones of body and limbs, this grouping has been revealed as incorrect. Rather, the similarities in skull morphology
reflect convergent evolution
to cope with the different challenges of daytime and nighttime feeding. Today, it is believed that three major groups can be distinguished, which are (from the most primitive to the most advanced):
The night herons could warrant separation as subfamily Nycticoracinae, as it was traditionally done. However, the position of some genera (e.g. Butorides or Syrigma) is unclear at the moment, and molecular studies have until now suffered from a small number of studied taxa. Especially the relationship among the ardeine subfamily is very badly resolved. The arrangement presented here should be considered provisional.
Recent DNA evidence suggests that this family belongs to the Pelecaniformes
. In response to these findings, the International Ornithological Congress
(IOC) recently reclassified Ardeidae and their sister taxa Threskiornithidae
under the order Pelecaniformes
instead of the previous order of Ciconiiformes
.
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Subfamily Tigrisomatinae
Subfamily Botaurinae
Subfamily Ardeinae
Fossil herons of unresolved affiliations:
Other prehistoric and fossil species are included in the respective genus accounts
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 family Ardeidae. There are 64 recognised species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
in this family. Some are called "egret
Egret
An egret is any of several herons, most of which are white or buff, and several of which develop fine plumes during the breeding season. Many egrets are members of the genera Egretta or Ardea which contain other species named as herons rather than egrets...
s" or "bittern
Bittern
Bitterns are a classification of birds in the heron family, Ardeidae, a family of wading birds. Species named bitterns tend to be the shorter-necked, often more secretive members of this family...
s" instead of "heron".
Within the family, all members of the genera Botaurus and Ixobrychus are referred to as "bitterns", and — including the Zigzag Heron
Zigzag Heron
The Zigzag Heron is a species of heron in the Ardeidae family, also including egrets and bitterns. It is in the monotypic genus Zebrilus....
or Zigzag Bittern — are a monophyletic group within the Ardeidae. However, egrets are not a biologically distinct group from the herons, and tend to be named differently because they are mainly white and/or have decorative plumes. Although egrets have the same build as the larger herons, they tend to be smaller.
The classification of the individual heron/egret species is fraught with difficulty, and there is still no clear consensus about the correct placement of many species into either of the two major genera, Ardea
Ardea (genus)
Ardea is a genus of herons. Linnaeus named this genus as the Great Herons, referring to the generally large size of these birds, typically 80–100 cm or more in length....
and Egretta
Egretta
Egretta is a genus of medium-sized herons, mostly breeding in warmer climates. Representatives of this family are found in most of the world, and the Little Egret, as well as being widespread throughout much of the Old World, has now started to colonise the Americas.These are typical egrets in...
. Similarly, the relationship of the genera
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...
in the family is not completely resolved. However, one species formerly considered to constitute a separate monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
family Cochlearidae, the Boat-billed Heron
Boat-billed Heron
The Boat-billed Heron - colloquially known as the Boatbill - is an atypical member of the heron family, and was formerly thought to be in a monotypic family, Cochlearidae....
, is now regarded as a member of the Ardeidae.
Although herons resemble birds in some other families, such as the stork
Stork
Storks are large, long-legged, long-necked wading birds with long, stout bills. They belong to the family Ciconiidae. They are the only family in the biological order Ciconiiformes, which was once much larger and held a number of families....
s, ibis
Ibis
The ibises are a group of long-legged wading birds in the family Threskiornithidae....
es and spoonbill
Spoonbill
Spoonbills are a group of large, long-legged wading birds in the family Threskiornithidae, which also includes the Ibises.All have large, flat, spatulate bills and feed by wading through shallow water, sweeping the partly opened bill from side to side...
s, they differ from these in flying with their necks retracted, not outstretched. They are also one of the bird groups that have powder down.
Some members of this group nest colonially
Bird colony
A bird colony is a large congregation of individuals of one or more species of bird that nest or roost in close proximity at a particular location. Many kinds of birds are known to congregate in groups of varying size; a congregation of nesting birds is called a breeding colony...
in trees; others, notably the bitterns, use reedbeds.
Description
The herons are medium to large sized birds with long legs and necks. They exhibit very little sexual dimorphismSexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
in size. The smallest species is usually considered the Little Bittern
Little Bittern
The Little Bittern is a wading bird in the heron family Ardeidae, native to the Old World, breeding in Africa, central and southern Europe, western and southern Asia, and Madagascar. Birds from temperate regions in Europe and western Asia are migratory, wintering in Africa and further south in...
, although all the species in the Ixobrychus
Ixobrychus
Ixobrychus is a genus of bitterns, a group of wading bird in the heron family Ardeidae. It has a single representative species in each of North America, South America, Eurasia and Australasia...
genus are small and many broadly overlap in size. The largest species of heron is the Goliath Heron
Goliath Heron
The Goliath Heron is a very large wading bird of the heron family Ardeidae. It is found in sub-Saharan Africa, with smaller numbers in Southwest and South Asia.-Description:This is the world's largest heron...
. The necks are able to kink in an s-shape, due to the modified shape of the sixth vertebrae. The neck is able to retract and extend, and is retracted during flight, unlike most other long-necked birds. The neck is longer in the day herons than the night herons and bitterns. The legs are long and strong and in almost every species are unfeathered from the lower part of the tibia (the exception is the Zigzag Heron
Zigzag Heron
The Zigzag Heron is a species of heron in the Ardeidae family, also including egrets and bitterns. It is in the monotypic genus Zebrilus....
). In flight the legs and feet are held backward. The feet of herons have long thin toes, with three forward pointing ones and one going backward.
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
is generally long and harpoon like. It can vary from extremely fine, as in the Agami Heron
Agami Heron
The Agami Heron is a medium-sized heron. It is a resident breeding bird from Central America south to Peru and Brazil.It is sometimes known as the Chestnut-bellied Heron, and is the only member of the genus Agamia .The Agami Heron's habitat is forest swamps and similar wooded wetlands...
, to thick as in the Grey Heron
Grey Heron
The Grey Heron , is a wading bird of the heron family Ardeidae, native throughout temperate Europe and Asia and also parts of Africa. It is resident in the milder south and west, but many birds retreat in winter from the ice in colder regions...
. The most atypical bill is owned by the Boat-billed Heron
Boat-billed Heron
The Boat-billed Heron - colloquially known as the Boatbill - is an atypical member of the heron family, and was formerly thought to be in a monotypic family, Cochlearidae....
, which has a broad thick bill. The bill, as well as other bare parts of the body, is usually yellow, black or brown coloured, although this colour can vary during the breeding season. The feather
Feather
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...
s of the herons are soft. The plumage
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
of the herons is usually blue, black, brown, grey or white, and can often be strikingly complex. Amongst the day herons there is little sexual dimorphism in plumage (except in the pond-herons); differences between the sexes are the rule for the night herons and smaller bitterns. Many species also have different colour morphs. In the Pacific Reef Heron there are both dark and light colour morphs, and the percentage of each morph varies geographically. White morphs only occur in areas with coral beaches.
Distribution, habitat and movements
The herons are a widespread family with a cosmopolitan distributionCosmopolitan distribution
In biogeography, a taxon is said to have a cosmopolitan distribution if its range extends across all or most of the world in appropriate habitats. For instance, the killer whale has a cosmopolitan distribution, extending over most of the world's oceans. Other examples include humans, the lichen...
. They exist on all continents except Antarctica, and are present in most habitats except the coldest extremes of the Arctic, extremely high mountains and the driest deserts. Almost all species are associated with water, they are essentially non-swimming waterbirds that feed on the margins of lakes, rivers, swamps, ponds and the sea. They are predominately found in lowland areas, although some species live in alpine areas, and the majority of species occur in the tropics.
The herons are a highly mobile family, with most species being at least partially migratory
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...
. Some species are partially migratory, for example the Grey Heron
Grey Heron
The Grey Heron , is a wading bird of the heron family Ardeidae, native throughout temperate Europe and Asia and also parts of Africa. It is resident in the milder south and west, but many birds retreat in winter from the ice in colder regions...
, which is mostly sedentary in Britain but mostly migratory in Scandinavia. Birds are particularly inclined to disperse widely after breeding but before the annual migration where the species is colonial, searching out new feeding areas and reducing the pressures on feeding grounds near the colony. The migration typically occurs at night, usually as individuals or in small groups.
Diet
The herons and bitterns are carnivorous. The members of this family are mostly associated with wetlands and water, and feed on a variety of live aquatic prey. The diet includes a wide variety of aquatic animals, including fish, reptiles, amphibians, crustaceans, molluscs and aquatic insects. Individual species may be generalists or specialise in certain prey types, like the Yellow-crowned Night HeronYellow-crowned Night Heron
The Yellow-crowned Night Heron , also called the American Night Heron or squawk, is a fairly small heron, similar in appearance to the Black-crowned Night Heron...
, which specialises in crustaceans, particularly crabs. Many species will also opportunistically take larger prey, including birds and bird eggs, and more rarely carrion. Even more rarely there have been reports of herons eating acorns, peas and grains, but most vegetable matter consumed is accidental.
The most common hunting technique is for the bird to sit motionless on the edge of or standing in shallow water and wait until prey comes within range. Birds may either do this from an upright posture, giving them a wider field of view for seeing prey, or from a crouched position, which is more cryptic and means the bill is closer to the prey when it is located. Having seen prey the head is moved from side to side, so that the heron can calculate the position of the prey in the water and compensate for refraction
Refraction
Refraction is the change in direction of a wave due to a change in its speed. It is essentially a surface phenomenon . The phenomenon is mainly in governance to the law of conservation of energy. The proper explanation would be that due to change of medium, the phase velocity of the wave is changed...
, and then the bill is used to spear the prey.
In addition to sitting and waiting, herons may feed more actively. They may walk slowly, at around or less than 60 paces a minute, snatching prey when it is observed. Other active feeding behaviours include foot stirring and probing, where the feet are used to flush out hidden prey. The wings may be used to frighten prey (or possibly attract it to shade) or to reduce glare; the most extreme example of this is exhibited by the Black Heron
Black Heron
The Black Heron also known as the Black Egret, is an African heron. It is a medium-sized , black-plumaged heron with yellow legs and feet. It is found south of the Sahara Desert, including Madagascar, and prefers shallow open waters, such as the edges of freshwater lakes and ponds...
, which forms a full canopy with its wings over its body.
Some species of heron , such as the Little Egret
Little Egret
The Little Egret is a small white heron. It is the Old World counterpart to the very similar New World Snowy Egret.-Subspecies:Depending on authority, two or three subspecies of Little Egret are currently accepted....
and Grey Heron
Grey Heron
The Grey Heron , is a wading bird of the heron family Ardeidae, native throughout temperate Europe and Asia and also parts of Africa. It is resident in the milder south and west, but many birds retreat in winter from the ice in colder regions...
, have been documented using bait in order to lure prey to within striking distance. Herons may use items already in place, or actively add items to the water in order to attract fish. Items used may be man made, such as bread; alternatively Striated Heron
Striated Heron
The Striated Heron, Butorides striata, also known as Mangrove Heron, Little Heron or Green-backed Heron, is a small heron. Striated Herons are mostly non-migratory and noted for some interesting behavioral traits. Their breeding habitat is small wetlands in the Old World tropics from west Africa to...
s in the Amazon
Amazon Basin
The Amazon Basin is the part of South America drained by the Amazon River and its tributaries that drains an area of about , or roughly 40 percent of South America. The basin is located in the countries of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, and Venezuela...
have been watched repeatedly dropping seeds, insects, flowers and leaves into the water to catch fish.
Three species, 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....
, Whistling Heron
Whistling Heron
The Whistling Heron is a medium-sized, often terrestrial heron of South America. There are two subspecies, the southern S. s. sibilatrix and the northern S. s. fostersmithi.-Description:...
and especially the Cattle Egret
Cattle Egret
The Cattle Egret is a cosmopolitan species of heron found in the tropics, subtropics and warm temperate zones. It is the only member of the monotypic genus Bubulcus, although some authorities regard its two subspecies as full species, the Western Cattle Egret and the Eastern Cattle Egret...
are less tied to watery environments and may feed far away from water. Cattle Egrets improve their foraging success by following large grazing animals, catching insects flushed by their movement. One study found that the success rate of prey capture increased 3.6 times over solitary foraging.
Breeding
Monogamy
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...
and mostly colonial
Bird colony
A bird colony is a large congregation of individuals of one or more species of bird that nest or roost in close proximity at a particular location. Many kinds of birds are known to congregate in groups of varying size; a congregation of nesting birds is called a breeding colony...
. Most day-herons and night-herons are colonial, or partly colonial depending on circumstances, whereas the bitterns and tiger-herons are mostly solitary nesters. Colonies may contain several species as well as other types of waterbird. In a study of Little Egrets and Cattle Egrets in India the majority of the colonies surveyed contained both species. Nesting is seasonal in temperate species; in tropical species it may be seasonal (often coinciding with the rainy season) or year-round. Even in year-round breeders nesting intensity varies throughout the year. Tropical herons typically have only one breeding season per year, unlike some other tropical birds which may raise up to three broods a year.
Courtship usually takes part on the nest
Bird nest
A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American Robin or Eurasian Blackbird, or the elaborately woven hanging nest of the...
. Males arrive first and begin the building of the nest, where they display to attract females. In colonial species displays involve visual cues, which can include adopting postures or ritual displays, whereas in solitary species auditory cues, such as the deep booming of the bitterns, are important. The exception to this is the Boat-billed Heron, which pairs up away from the nesting site. Having paired the pair continue to build the nest in almost all species, although in the Little Bittern
Little Bittern
The Little Bittern is a wading bird in the heron family Ardeidae, native to the Old World, breeding in Africa, central and southern Europe, western and southern Asia, and Madagascar. Birds from temperate regions in Europe and western Asia are migratory, wintering in Africa and further south in...
and Least Bittern
Least Bittern
The Least Bittern is a small wading bird, the smallest heron found in the Americas.This bird's underparts and throat are white with light brown streaks. Their face and the sides of the neck are light brown; they have yellow eyes and a yellow bill. The adult male is glossy greenish black on the...
only the male works on the nest.
Some ornithologists
Ornithology
Ornithology is a branch of zoology that concerns the study of birds. Several aspects of ornithology differ from related disciplines, due partly to the high visibility and the aesthetic appeal of birds...
have reported observing female herons attaching themselves to impotent
Erectile dysfunction
Erectile dysfunction is sexual dysfunction characterized by the inability to develop or maintain an erection of the penis during sexual performance....
mates, then seeking sexual gratification elsewhere.
The nests of herons are usually found near or above water. They are typically placed in vegetation, although the nests of a few species have been found on the ground where suitable trees of shrubs are unavailable. Trees are used by many species, and here they may be placed high up from the ground, whereas species living in reedbeds may nest very close to the ground.
Generally herons lay between three to seven eggs
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...
. Larger clutches are reported in the smaller bitterns and more rarely some of the larger day-herons, and single egg clutches are reported for some of the tiger-herons. Clutch size varies by latitude within species, with individuals in temperate climates laying more eggs than tropical ones. On the whole the eggs are glossy blue or white, with the exception being the large bitterns which lay olive-brown eggs.
Name
Herons are also known as "shitepokes" (pron), or euphemistically as "shikepokes" or "shypokes". Webster's DictionaryWebster's Dictionary
Webster's Dictionary refers to the line of dictionaries first developed by Noah Webster in the early 19th century, and also to numerous unrelated dictionaries that added Webster's name just to share his prestige. The term is a genericized trademark in the U.S.A...
suggests that herons were given this name because of their habit of defecating when flushed. The terms "shitepoke" or "shikepoke" can be used as insults in a number of situations. For example, the term "shikepoke" appears in the 1931 play Green Grow The Lilacs
Green Grow the Lilacs (play)
Green Grow the Lilacs is a 1930 play by Lynn Riggs named for the popular folk song of the same name. It was performed 64 times on Broadway, opening on January 26, 1931 and closing March 21, 1931. It also played January 19, 1931 through January 24, 1931 at the National Theatre in Washington, D.C. It...
, and in the 1943 musical play Oklahoma!
Oklahoma!
Oklahoma! is the first musical written by composer Richard Rodgers and librettist Oscar Hammerstein II. The musical is based on Lynn Riggs' 1931 play, Green Grow the Lilacs. Set in Oklahoma Territory outside the town of Claremore in 1906, it tells the story of cowboy Curly McLain and his romance...
.
The 1971 Compact Edition of the Oxford English Dictionary describes the use of "shitepoke" for the small green heron of North America (Butorides virescens) as originating in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, citing a published example from 1853. The OED also observes that "shiterow" or "shederow" are terms used for herons, and also applied as derogatory terms meaning a "thin weakly person". This name for a heron is found in a list of gamebirds in a royal decree of James VI (1566–1625) of Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
. The OED speculates that "shiterow" is a corruption of "shiteheron".
Taxonomy and systematics
Analyses of the skeleton, mainly the skullSkull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
, suggested that the Ardeidae could be split into a diurnal
Diurnal animal
Diurnality is a plant or animal behavior characterized by activity during the day and sleeping at night.-In animals:Animals that are not diurnal might be nocturnal or crepuscular . Many animal species are diurnal, including many mammals, insects, reptiles and birds...
and a crepuscular
Crepuscular
Crepuscular animals are those that are active primarily during twilight, that is during dawn and dusk. The word is derived from the Latin word crepusculum, meaning "twilight." Crepuscular is, thus, in contrast with diurnal and nocturnal behavior. Crepuscular animals may also be active on a bright...
/nocturnal group which included the bitterns. From DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
studies and skeletal analyses focusing more on bones of body and limbs, this grouping has been revealed as incorrect. Rather, the similarities in skull morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
reflect convergent evolution
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
to cope with the different challenges of daytime and nighttime feeding. Today, it is believed that three major groups can be distinguished, which are (from the most primitive to the most advanced):
- tiger herons and the boatbill
- bitterns
- day-herons and egrets, and night-herons
The night herons could warrant separation as subfamily Nycticoracinae, as it was traditionally done. However, the position of some genera (e.g. Butorides or Syrigma) is unclear at the moment, and molecular studies have until now suffered from a small number of studied taxa. Especially the relationship among the ardeine subfamily is very badly resolved. The arrangement presented here should be considered provisional.
Recent DNA evidence suggests that this family belongs to the Pelecaniformes
Pelecaniformes
The Pelecaniformes is a order of medium-sized and large waterbirds found worldwide. As traditionally—but erroneously—defined, they encompass all birds that have feet with all four toes webbed. Hence, they were formerly also known by such names as totipalmates or steganopodes...
. In response to these findings, the International Ornithological Congress
International Ornithological Congress
The International Ornithological Congress series forms the oldest and largest international series of meetings of ornithologists. It is organised by the International Ornithological Committee, a group of about 200 ornithologists...
(IOC) recently reclassified Ardeidae and their sister taxa Threskiornithidae
Threskiornithidae
The family Threskiornithidae includes 34 species of large terrestrial and wading birds, falling into two subfamilies, the ibises and the spoonbills. It was formerly known as Plataleidae. The spoonbills and ibises were once thought to be related to other groups of long-legged wading birds in the...
under the order Pelecaniformes
Pelecaniformes
The Pelecaniformes is a order of medium-sized and large waterbirds found worldwide. As traditionally—but erroneously—defined, they encompass all birds that have feet with all four toes webbed. Hence, they were formerly also known by such names as totipalmates or steganopodes...
instead of the previous order of Ciconiiformes
Ciconiiformes
Traditionally, the order Ciconiiformes has included a variety of large, long-legged wading birds with large bills: storks, herons, egrets, ibises, spoonbills, and several others. Ciconiiformes are known from the Late Eocene...
.
- Genus Cochlearius — Boat-billed Heron
- Genus TigrisomaTigrisomaTigrisoma is a genus of heron in the Ardeidae family.It contains the following species:* Bare-throated Tiger Heron, Tigrisoma mexicanum* Fasciated Tiger Heron, Tigrisoma fasciatum* Rufescent Tiger Heron, Tigrisoma lineatum...
— typical tiger herons (3 species) - Genus Tigriornis — White-crested Tiger Heron
- Genus Zonerodius — Forest Bittern
Subfamily Botaurinae
- Genus Zebrilus — Zigzag Heron
- Genus IxobrychusIxobrychusIxobrychus is a genus of bitterns, a group of wading bird in the heron family Ardeidae. It has a single representative species in each of North America, South America, Eurasia and Australasia...
— small bitterns (8 living species, 1 recently extinct) - Genus BotaurusBotaurusBotaurus is a genus of bitterns, a group of wading bird in the heron family Ardeidae. It has a single representative species in each of North America, Central and South America, Eurasia and Australasia...
— large bitterns (4 species)
Subfamily Ardeinae
- Genus ZeltornisZeltornisZeltornis is an extinct genus of heron. It contains a single species, Zeltornis ginsburgi.Zeltornis probably resembled the modern night herons, but was much larger, standing 2 m tall and weighing about 15 kg. Its wingspan is estimated at 2.50 m...
(fossilFossilFossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
) - Genus NycticoraxNycticoraxNycticorax is a genus of night herons. The name Nycticorax derives from the Greek for “night raven” and refers to the largely nocturnal feeding habits of this group of birds, and the croaking crow-like call of the best known species, the Black-crowned Night Heron.These are medium-sized herons which...
— typical night herons (2 living species, 4 recently extinct; includes Nyctanassa) - Genus NyctanassaNyctanassaNyctanassa is a genus of night herons from the Americas, especially warmer coastal regions. They were formerly included in the genus Nycticorax, but today all major authorities recognize them as different....
— American night herons (1 living species, 1 recently extinct) - Genus GorsachiusGorsachiusGorsachius is a genus of Old World night herons typically found near water in forested regions. These are medium-sized herons which are migratory in the colder parts of their ranges, but otherwise resident...
— Asian and African night herons (4 species) - Genus ButoridesButoridesButorides is a genus of small herons. It contains three similar species, the Green Heron or Green-backed Heron, Butorides virescens, the Lava Heron , and the Striated Heron, Butorides striatus...
— green-backed herons (3 species; sometimes included in Ardea) - Genus Agamia — Agami Heron
- Genus Pilherodius — Capped Heron
- Genus ArdeolaArdeolaArdeola is a genus of small herons, typically 40–50 cm long with 80–100 cm wingspan. Most breed in the tropical Old World, but the migratory Squacco Heron occurs in southern Europe and the Middle East and winters in Africa....
— pond herons (6 species) - Genus Bubulcus — cattle egrets (1-2 species, sometimes included in Ardea)
- Genus ProardeaProardeaProardea is an extinct genus of heron, containing a single species, Proardea amissa . It stood about 70 cm tall and was very similar to a modern heron in shape...
— (fossilFossilFossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
) - Genus ArdeaArdea (genus)Ardea is a genus of herons. Linnaeus named this genus as the Great Herons, referring to the generally large size of these birds, typically 80–100 cm or more in length....
— typical herons (11-17 species) - Genus Syrigma — Whistling Heron
- Genus EgrettaEgrettaEgretta is a genus of medium-sized herons, mostly breeding in warmer climates. Representatives of this family are found in most of the world, and the Little Egret, as well as being widespread throughout much of the Old World, has now started to colonise the Americas.These are typical egrets in...
— typical egrets (7-13 species) - Genus Mesophoyx — Intermediate Egret
- Genus undetermined
- Easter Island Heron, Ardeidae gen. et sp. indet. (prehistoricLate Quaternary prehistoric birdsPrehistoric birds are various taxa of birds that became extinct before recorded history, or more precisely, before they could be studied alive by bird scientists...
)
- Easter Island Heron, Ardeidae gen. et sp. indet. (prehistoric
Fossil herons of unresolved affiliations:
- Calcardea (Paleocene)
- Xenerodiops (Early Oligocene of Fayyum, Egypt)
- "Anas" basaltica (Late Oligocene of "Warnsdorf", Czechia)
- Ardeagradis
- Proardeola — possibly same as Proardea
Other prehistoric and fossil species are included in the respective genus accounts
External links
- HeronConservation Heron Specialist Group of IUCN
- Heron videos on the Internet Bird Collection