Cape Verde warbler (Acrocephalus brevipennis)

Also known as: cane warbler, Cape Verde cane warbler, Cape Verde cane-warbler, Cape Verde Islands cane warbler, Cape Verde Islands warbler, Cape Verde swamp warbler, Cape Verde swamp-warbler, Dohrn’s swamp-warbler
Synonyms: Calamodyta brevipennis
  
French: Rousserolle des Iles du Cap-Vert
KingdomAnimalia
PhylumChordata
ClassAves
OrderPasseriformes
FamilySylviidae
GenusAcrocephalus (1)
SizeLength: 14 - 16 cm (2) (3)
Weight15 - 17 g (2)
Top facts

The Cape Verde warbler is classified as Endangered (EN) on the IUCN Red List (1).

A medium-sized warbler with rather drab plumage (2) (3) (4), the Cape Verde warbler (Acrocephalus brevipennis) was thought to only inhabit one island in the world until its rediscovery on two others (3) (5). This small bird has greyish-brown plumage on its upperparts, which fades to creamy-white on its throat and breast (2) (3) (4). The rest of the Cape Verde warbler’s underparts have a grey to brown wash (2) (4), and a yellowish shade can sometimes be found on the chin, throat and belly (4).

The tail feathers of the Cape Verde warbler are mainly dark brown (4), while the wing feathers are dark grey, with the edges of the feathers fading into an olive brown. This species has a distinctive reddish-brown tinge to the rump (2) (4). Its face is marked with a faint, narrow, greyish-white line above the eye (2) (4) and it has a long, pointed, dark brown to blackish beak, with the lower part of the beak being yellow-orange (2). The Cape Verde warbler’s legs and toes are dark grey (2) (4). This species’ tail is quite long, and its wings are short and rounded (4).

The male and female Cape Verde warbler are similar in appearance (3) (4), while the juvenile has brighter, more reddish-brown plumage on the upperparts (2) (4). The juvenile’s tail and flight feathers are dark grey and the feathers of its body are fluffier than the body feathers of the adult. The plumage of the adults does not change colour significantly throughout the seasons, although the upperparts become greyer as the plumage becomes more worn (4).

The Cape Verde warbler sings a loud, resonant song all year round (2) (3) (4), with the songs being loudest during the breeding season (2) (3). The song consists of clear whistles and churring sounds given in short sequences (2) (3), and this species also uses a range of different calls, including a throaty ‘kerr-chow’ and a ‘chuk’ or ‘tuk’ (2) (4).

The Cape Verde warbler can be confused with the olivaceous warbler (Hippolais pallida), a species that has been recorded on the Cape Verde Islands, due to a similarity in colour and body form. However, the olivaceous warbler is smaller, and does not have a greyish wash on its breast (4).

As its name suggests, the Cape Verde warbler is found on the Cape Verde Islands (2), off the west coast of Africa (6). This species was originally thought to have an isolated existence on the island of Santiago (3) (5). However, it is now believed to inhabit the islands of Santiago, Fogo and São Nicolau (2) (3) (7), having been rediscovered on São Nicolau in 1998 and found on Fogo in 2004 (3) (5).

It is believed that the Cape Verde warbler has died out on the island of Brava (3) (5).

The Cape Verde warbler is found in a variety of habitats, such as reed beds, forests, well-vegetated valleys, and even gardens in towns (3) (4), generally preferring habitats with reeds and running water (4). This species is typically found in habitats that are below elevations of 1,000 metres (3).

The Cape Verde Islands’ lack of natural habitat has led to the Cape Verde warbler inhabiting artificial habitats, such as sugar cane plantations and gardens (4). On the island of Fogo, this species is mainly found in coffee plantations where there are fruit trees and crops, such as maize (3) (8). Populations found at higher elevations on Fogo seem to prefer inhabiting areas which contain flowering plants such as Spanish flag (Ipomoea lobata) and giant reed (Arundo donax) (8).

In the interior of Santiago, the Cape Verde warbler has been found living in eucalyptus forest with thick bushy undergrowth (3). On São Nicolau, the Cape Verde warbler inhabits small, dense stands of introduced giant reed (3) (5), often with shrubs and fruit trees (3).

The Cape Verde warbler breeds between August and November, although the breeding period might last longer if there has been rain (3). Breeding pairs are territorial (2) and may build their nest either above the ground or above water (9). The nests of the Cape Verde warbler are constructed predominantly in giant reed (Arundo donax), but also in sugarcane, bushes and trees (2) (9). The nests are made out of blades of maize and grass, and are suspended between vertical stems or twigs (9).

The female Cape Verde warbler generally produces two to three eggs (2) (8), and both the male and female warblers take it in turn to incubate and turn the eggs (5) (8). The male often perches in neighbouring trees, singing quietly, while the female incubates the eggs (5).

Individuals of this species flock together to form small groups outside of the breeding season (2), and these groups have been seen feeding in fig trees along with blackcaps (Sylvia atricapilla) (2) (3).

Little other information is available on the biology of the Cape Verde warbler, but it is reported to fly in a rather frail and fluttering fashion (4), and will fly up into the trees if it is spooked (2).

One reason for the decline in the Cape Verde warbler is thought to be the loss of its habitat, which has been caused by consecutive droughts and a greater number of people now living on the islands. This species is also threatened by disease and environmental disasters, particularly as its entire population is restricted to just three small islands (3).

Only a few Cape Verde warblers have been found on São Nicolau, and the long-term survival of the species on this island looks precarious (3) (5). However, the discovery of a relatively large population of Cape Verde warblers on Fogo may mean that this warbler is less threatened than previously thought (3).

There are no current conservation activities in place for the Cape Verde warbler, although Wildlife Protection Laws were drawn up in the late 1980s. However, these laws were never enacted, and so currently this species is not legally protected (3).

A number of conservation guidelines have been proposed by researchers for the Cape Verde warbler. These include implementing a programme to educate the public and the local authorities, studying the species’ habitat and threats, and targeting research towards the newly discovered population on the island of Fogo. It has also been suggested that farmers on the islands should be encouraged, through agricultural subsidies, to plant species that will increase the size of the Cape Verde warbler’s habitat (3).

Efforts to maintain, increase and irrigate stands of cane and fruit trees on São Nicolau may help the Cape Verde warbler to survive there (5). On the island of Brava, a thorough search should be conducted to determine whether this small bird is definitely extinct there (3).

Find out more about the Cape Verde warbler and its conservation:

Find out more about conservation on the Cape Verde Islands:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

  1. IUCN Red List (November, 2012)
    http://www.iucnredlist.org/
  2. Kennerley, P. and Pearson, D. (2010) Reed and Bush Warblers. Christopher Helm Publishers, London.
  3. BirdLife International - Cape Verde warbler (November, 2012)
    http://www.birdlife.org/datazone/speciesfactsheet.php?id=7624
  4. Baker, K. (1997) Warblers of Europe, Asia and North Africa. Christopher Helm Publishers, London.
  5. Donald, P.F., Taylor, R., de Ponte Machado, M., Pitta Groz, M.J., Wells, C.E., Marlow, T. and Hille, S.M. (2004) Status of the Cape Verde cane warbler Acrocephalus brevipennis on São Nicolau, with notes on song, breeding behaviour and threats. Malimbus, 26: 34-37.
  6. Bourne, W.R.P. (1995) The birds of the Cape Verde Islands. Ibis, 97(3): 508-556.
  7. Hazevoet, C.J. (2010) Sixth report on birds from the Cape Verde Islands, including records of 25 taxa new to the archipelago. Zoologia Caboverdiana, 1(1): 3-44.
  8. Hering, J. and Fuchs, E. (2009) Der Kapverdenrohrsänger Acrocephalus brevipennis auf Fogo (Kapverdische Inseln): Verbreitung, Dichte, Habitat und Brutbiologie. Vogelwarte, 47: 157-164.
  9. Bocheński, Z. and Kuśnierczyk, P. (2003) Nesting of the Acrocephalus warblers. Acta Zoologica Cracoviensia, 46(2): 97-195.