Eastern olivaceous warbler (Hippolais pallida)
|Also known as:||olivaceous warbler|
|Size||Length: 12 - 14 cm (2)|
|Weight||8 - 16 g (2)|
Classified as Least Concern (LC) on the IUCN Red List (1).
The eastern olivaceous warbler is a predominantly greyish-brown warbler with a fairly long, pointed beak, a narrow, square-ended tail, and a rather peaked crown on the head (2) (3). The wings are relatively short and rounded (3). The plumage of this species is quite nondescript, being uniformly grey-brown or pale brown on the upperparts, with a slightly reddish-brown tinge, and whiter on the underparts, with a buffy tinge on the sides of the breast and the flanks. The head bears a short, indistinct, whitish stripe above the eye and a pale eye ring. The upper mandible of the beak is dark, while the lower mandible is pinkish-yellow, and the legs are greyish (2) (3). The male and female eastern olivaceous warbler are similar in appearance, and juveniles also resemble the adults (2), but may have a slightly more buffy rump (3). The song of the eastern olivaceous warbler is quite loud and consists of fairly monotonous, scratchy and chattering phrases, repeated at a steady tempo. The species’ call is described as a check, tec or click note (2) (3).
A number of subspecies of eastern olivaceous warbler have been recognised, which differ mainly in size and in the tone of the plumage (2). However, the former subspecies Hippolais pallida opaca is now considered a separate species, the western olivaceous warbler (Hippolais opaca), based on differences in its size, appearance and song, and on genetic differences (4).
The eastern olivaceous warbler breeds across North Africa, south-eastern Europe, the Arabian Peninsula and into central Asia. In winter, it migrates south of the Sahara to East Africa, as well as spending the winter locally in south-western Arabia (2) (5).
This species lives in trees and bushes in a range of habitats, including parks, cultivated areas, gardens, plantations, trees beside rivers or lakes, and palm oases (2) (3). It prefers areas with at least some tall vegetation, often close to water, and appears to require patchy, fragmented woodland rather than closed forest (2). In some areas, the eastern olivaceous warbler appears to prefer breeding within human settlements (6).
The eastern olivaceous warbler feeds mainly on insects and other invertebrates, although it will also take fruit such as berries in late summer (2), and has even been recorded feeding on nectar during migration (7). Foraging typically takes place in the canopy, with prey picked from leaves and twigs, but this warbler will also feed on the ground and often forages in low scrub on migration (2). The eastern olivaceous warbler has a distinctive habit of repeatedly flicking the tail downwards while foraging (3), often accompanying each tail dip with a call (2).
The eastern olivaceous warbler breeds between May and June, usually building the nest in the fork of a branch. The nest is a well-built cup, constructed from plant stems and soft twigs and lined with plant material and fur (2). Two to five eggs are laid (2) (6), and hatch after 11 to 13 days. The female alone incubates the eggs, but both adults feed the chicks, which fledge at 11 to 15 days old (2). The nests of this species are often parasitized by cuckoos (Cuculus canorus) (6).
The eastern olivaceous warbler is a widespread and common species, and is not currently considered at risk of extinction (5). As it often breeds within human settlements (6), it may be able to tolerate some degree of habitat disturbance.
The eastern olivaceous warbler is listed on Appendix II of the Convention on Migratory Species, which aims to conserve migratory species throughout their range (8). There are not known to be any other conservation measures currently targeted at this species.
To find out more about the eastern olivaceous warbler and its conservation, see:
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- Brood parasitism: a brood parasite is an animal that lays its eggs in the nests of members of its own or other species; the host then raises the young as its own.
- Incubate: to keep eggs warm so that development is possible.
- Invertebrates: animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones) and echinoderms.
- Mandible: in birds, the lower jaw and beak, but the term is also used to denote the two parts of the beak.
- Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
IUCN Red List (October, 2010)
- del Hoyo, J., Elliott, A. and Christie, D. (2006) Handbook of the Birds of the World. Volume 11: Old World Flycatchers to Old World Warblers. Lynx Edicions, Barcelona.
- Peterson, R.T., Mountfort, G. and Hollom, P.A.D. (1993) Collins Field Guide: Birds of Britain and Europe. HarperCollins Publishers, London.
- Ottosson, U., Bensch, S., Svensson, L. and Waldenström, J. (2005) Differentiation and phylogeny of the olivaceous warbler Hippolais pallida species complex. Journal of Ornithology, 146: 127-136.
BirdLife International (October, 2010)
- Antonov, A., Stokke, B.G., Moksnes, A. and Røskaft, E. (2007) Aspects of breeding ecology of the eastern olivaceous warbler (Hippolais pallida). Journal of Ornithology, 148: 443-451.
- Salewski, V., Almasi, B. and Schlageter, A. (2006) Nectarivory of Palearctic migrants at a stopover site in the Sahara. British Birds, 99: 299-305.
Convention on the Conservation of Migratory Species of Wild Animals (October, 2010)