The Cape Verde Swamp Warbler (Acrocephalus brevipennis) is an 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...

 in the genus 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 is also known by the name Cape Verde Cane Warbler (or simply Cape Verde Warbler). It breeds both on Santiago

Santiago, Cape Verde

Santiago , or Santiagu in Cape Verdean Creole, is the largest island of Cape Verde, its most important agricultural centre and home to half the nation’s population. At the time of Darwin's voyage it was called St. Jago....

 and on Fogo

Fogo, Cape Verde

Fogo is an island in the Sotavento group of Cape Verde. It is the most prominent of the group, rising to nearly 3,000 m above sea level at Pico do Fogo.-Geography:...

 in the Cape Verde Islands. It previously bred on Brava and San Nicolau. This small 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 is found in well-vegetated valleys, avoiding drier areas. It nests in reedbeds, 2–3 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 suspended nest.

This is a medium-sized warbler, larger than the Eurasian Reed Warbler. It resembles that bird in appearance, grey-brown above, greyish-white below, with no obvious markings. The geographical isolation of the bird on the Cape Verde Islands prevents confusion with other similar species. The song is a distinctive liquid bubbling, like that of a bulbul

Bulbul

Bulbuls are a family, Pycnonotidae, of medium-sized passerine songbirds. Many forest species are known as greenbuls. The family is distributed across most of Africa and into the Middle East, tropical Asia to Indonesia, and north as far as Japan. A few insular species occur on the tropical islands...

.