The river warbler (''Locustella fluviatilis'') is an

Old World warbler Old World warblers are 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 ci ...

in the grass warbler genus ''Locustella''. It breeds in eastern and central

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

, and into the western

Palearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sibe ...

. It is migratory, wintering in inland southern

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

, from around the Zambezi River south to the vicinity of

Pretoria Pretoria () is South Africa's administrative capital, serving as the seat of the Executive (government), executive branch of government, and as the host to all foreign embassies to South Africa. Pretoria straddles the Apies River and extends ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

. The genus name ''Locustella'' is from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

and is a diminutive of ''locusta'', "grasshopper". This refers to the song of the

common grasshopper warbler The common grasshopper warbler (''Locustella naevia'') is a species of Old World warbler in the grass warbler genus ''Locustella''. It breeds across much of temperate Europe and the western Palearctic. It is migratory, wintering in north and we ...

and some others in this genus. The specific ''fluviatilis'' is

for "of a river". This small

passerine A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by t ...

bird is a species found in dense deciduous vegetation close to water in bogs or near a river. Five to seven eggs are laid in a nest in a tussock or on the ground. This species is a rare vagrant to western

. In Britain, a small number of males have set up

territories A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or an ...

in spring, including a bird in

Greater Manchester Greater Manchester is a metropolitan county and combined authority, combined authority area in North West England, with a population of 2.8 million; comprising ten metropolitan boroughs: City of Manchester, Manchester, City of Salford, Salford ...

in 1995. One exceptional vagrant was photographed in Gambell, Alaska, in October 2017. This is a largish warbler. The adult has an unstreaked grey-brown back, whitish grey underparts, and a darker undertail, which has white feather tips giving a contrasting pattern. The sexes are identical, as with most warblers, but young birds are yellower below. Like most warblers, it is

insectivorous A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores were ...

. Some birds can show reduced dark markings on the

undertail covert A covert feather or tectrix on a bird is one of a set of feathers, called coverts (or ''tectrices''), which, as the name implies, cover other feathers. The coverts help to smooth airflow over the wings and tail. Ear coverts The ear coverts are sm ...

s (caused by more extensive than usual white tips) and thus are closer in appearance to Savi's warbler than typical river warblers. However, they typically still have a streaked breast and more olive colouration on the upperparts.Normaja, Jyrki (1994) Plumage variation in River Warblers '' Birding World'' 7(5): 192-5 This is a skulking species which is very difficult to see except sometimes when singing. It creeps through grass and low foliage. The song is a monotonous mechanical

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...

-like reeling, often given at dusk. It is similar to the song of other species in the group, but has more of a sewing machine quality, and may be produced for long periods.

References

External links

Images at www.naturlichter.com
{{Taxonbar, from=Q747787 river warbler Birds of Europe Birds of Western Asia river warbler