Great Reed Warbler
Encyclopedia
The Great Reed Warbler, Acrocephalus arundinaceus, is an Eurasia
an songbird
in the genus
Acrocephalus
. It used to be placed in the "Old World warbler
" assemblage, but nowadays is recognized to be part of the marsh- and tree-warbler family
(Acrocephalidae
).
-sized warbler
, 16–20 cm in length. The adult has an unstreaked brown upperparts and dull buffish-white chin and underparts. The forehead is flattened, and the bill is strong and pointed. It looks very much like a giant Eurasian Reed Warbler (A. scirpaceus), but with a stronger supercilium
.
The sexes are identical, as with most old world warblers, but young birds are richer buff below.
The song is very loud and far-carrying. Its main phrase is a chattering and creaking carr-carr-cree-cree-cree-jet-jet, to which the whistles and vocal mimicry typical of marsh-warblers are added.
A. arundinaceus breeds in Europe
and westernmost temperate
Asia
. It does not breed in Great Britain
, but is a regular visitor. Its population has in recent decades increased around the eastern Baltic
, while it has become rarer at the western end of its range. It is migratory
, wintering in tropical Africa
. This bird migrates north at a rather late date, with some birds still in winter quarters at the end of April.
While no subspecies
are diagnosable in this bird, mtDNA haplotype
data indicates that during the last glacial period there were two allopatric populations of this species. The Great Reed Warblers in southwestern and southeastern Europe were at that time apparently separated by the Vistulian-Würm ice sheet
s and the barren land around these. Though the data is insufficient to robustly infer
a date for this separation, it suggests the populations became separated around 80,000 years ago – coincident with the first major advance of the ice sheets. The populations must have expanded their range again at the start of the Holocene
about 13,000 years ago, but even today the western birds winter in the west and the eastern birds in the east of tropical Africa.
This passerine
bird
is a species found in large reed bed
s, often with some bushes. On their breeding grounds, they are territorial
. In their winter quarters, they are frequently found in large groups, and may occupy a reed bed to the exclusion of almost all other birds. Like most warblers, it is insectivorous, but it will take other prey items of sufficiently small size, even including vertebrate
s such as tadpole
s.
3-6 egg
s are laid in a basket nest in reeds. Some pairs are monogamous, but others are not, and unpaired males without territory usually father some young also.
The Great Reed Warbler apparently undergoes marked long-term population fluctuations. Able to expand its range again quickly when new habitat
becomes available, this common and widespread bird is considered a Species of Least Concern
by the IUCN.
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
an songbird
Songbird
A songbird is a bird belonging to the suborder Passeri of the perching birds . Another name that is sometimes seen as scientific or vernacular name is Oscines, from Latin oscen, "a songbird"...
in the 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...
Acrocephalus
Acrocephalus
The Acrocephalus warblers are small, insectivorous passerine birds belonging to the genus Acrocephalus. Formerly in the paraphyletic Old World warbler assemblage, they are now separated as the namesake of the marsh- and tree-warbler family Acrocephalidae...
. It used to be placed in the "Old World warbler
Old World warbler
The "Old World Warblers" is the name used to describe a large group of birds formerly grouped together in the bird family Sylviidae. The family held over 400 species in over 70 genera, and were the source of much taxonomic confusion. Two families were split out initially, the cisticolas into...
" assemblage, but nowadays is recognized to be part of the marsh- and tree-warbler 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...
(Acrocephalidae
Acrocephalidae
Acrocephalidae is a family of oscine passerine birds, in the superfamily Sylvioidea....
).
Description
This is a large thrushThrush (bird)
The thrushes, family Turdidae, are a group of passerine birds that occur worldwide.-Characteristics:Thrushes are plump, soft-plumaged, small to medium-sized birds, inhabiting wooded areas, and often feed on the ground or eat small fruit. The smallest thrush may be the Forest Rock-thrush, at and...
-sized warbler
Warbler
There are a number of Passeriformes called "warblers". They are not particularly closely related, but share some characteristics, such as being fairly small, vocal and insectivorous....
, 16–20 cm in length. The adult has an unstreaked brown upperparts and dull buffish-white chin and underparts. The forehead is flattened, and the bill is strong and pointed. It looks very much like a giant Eurasian Reed Warbler (A. scirpaceus), but with a stronger supercilium
Supercilium
The supercilium is a plumage feature found on the heads of some bird species. It is a stripe which runs from the base of the bird's beak above its eye, finishing somewhere towards the rear of the bird's head. Also known as an "eyebrow", it is distinct from the eyestripe, which is a line which runs...
.
The sexes are identical, as with most old world warblers, but young birds are richer buff below.
The song is very loud and far-carrying. Its main phrase is a chattering and creaking carr-carr-cree-cree-cree-jet-jet, to which the whistles and vocal mimicry typical of marsh-warblers are added.
Distribution and ecology
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and westernmost temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
. It does not breed in Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...
, but is a regular visitor. Its population has in recent decades increased around the eastern Baltic
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...
, while it has become rarer at the western end of its range. It is 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...
, wintering in tropical Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
. This bird migrates north at a rather late date, with some birds still in winter quarters at the end of April.
While 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...
are diagnosable in this bird, mtDNA haplotype
Haplotype
A haplotype in genetics is a combination of alleles at adjacent locations on the chromosome that are transmitted together...
data indicates that during the last glacial period there were two allopatric populations of this species. The Great Reed Warblers in southwestern and southeastern Europe were at that time apparently separated by the Vistulian-Würm ice sheet
Ice sheet
An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² , thus also known as continental glacier...
s and the barren land around these. Though the data is insufficient to robustly infer
Inference
Inference is the act or process of deriving logical conclusions from premises known or assumed to be true. The conclusion drawn is also called an idiomatic. The laws of valid inference are studied in the field of logic.Human inference Inference is the act or process of deriving logical conclusions...
a date for this separation, it suggests the populations became separated around 80,000 years ago – coincident with the first major advance of the ice sheets. The populations must have expanded their range again at the start of the Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
about 13,000 years ago, but even today the western birds winter in the west and the eastern birds in the east of tropical Africa.
This passerine
Passerine
A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...
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...
is a species found in large 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, often with some bushes. On their breeding grounds, they are territorial
Territory (animal)
In ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...
. In their winter quarters, they are frequently found in large groups, and may occupy a reed bed to the exclusion of almost all other birds. Like most warblers, it is insectivorous, but it will take other prey items of sufficiently small size, even including 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...
s such as tadpole
Tadpole
A tadpole or polliwog is the wholly aquatic larval stage in the life cycle of an amphibian, particularly that of a frog or toad.- Appellation :...
s.
3-6 egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
s are laid in a basket nest in reeds. Some pairs are monogamous, but others are not, and unpaired males without territory usually father some young also.
The Great Reed Warbler apparently undergoes marked long-term population fluctuations. Able to expand its range again quickly when new habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
becomes available, this common and widespread bird is considered a Species of 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...
by the IUCN.