Western olivaceous warbler

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Western olivaceous warbler
Iduna opaca CDC image.jpg
collected in Zouala, Morocco, April 2011
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Acrocephalidae
Genus: Iduna
I. opaca
Binomial name
Iduna opaca
Cabanis, 1850
Iduna opaca distribution map.png

Hippolais opaca

The western olivaceous warbler, also known as isabelline warbler,[2] (Iduna opaca) is a "warbler", formerly placed in the Old World warblers when these were a paraphyletic wastebin taxon. It is now considered a member of the acrocephaline warblers, Acrocephalidae, in the tree warbler genus Iduna. It was formerly regarded as part of a wider "olivaceous warbler" species, but as a result of modern taxonomic developments, this species is now usually considered distinct from the eastern olivaceous warbler, Iduna pallida.

Eggs, Collection Museum Wiesbaden

It is a small passerine bird, found in dry open country, including cultivation, with bushes or some trees. 2-3 eggs are laid in a nest in low in undergrowth or a bush. Like most warblers, western olivaceous warbler is insectivorous.

It is a medium-sized warbler, more like a very pale reed warbler than its relative the melodious warbler. The adults have a plain pale brown back and whitish underparts. The bill is strong and pointed and the legs grey. The sexes are identical, as with most warblers, but young birds are more buff on the belly. It has a characteristic downward tail flick.

Western olivaceous warbler breeds in Iberia and north Africa. It is migratory, wintering in sub-Saharan Africa. It is a rare vagrant to northern Europe.

Western olivaceous warbler is larger and has a browner tinge to the upperparts than eastern olivaceous warbler. It also has a larger bill. The song is a fast nasal babbling.


North Africa[edit]

Western olivaceous warbler occurs mainly a passage migrant in southeast Morocco, although it also may breed in some densely vegetated areas there.[3]


  1. ^ BirdLife International (2019). "Iduna opaca". IUCN Red List of Threatened Species. 2019: e.T22734089A155573383. doi:10.2305/IUCN.UK.2017-3.RLTS.T22734089A155573383.en. Retrieved 11 November 2021.
  2. ^ Del Hoyo, J.; Elliot, A. & Christie D. (editors). (2006). Handbook of the Birds of the World Volume 11: Old World Flycatchers to Old World Warblers. Lynx Edicions. ISBN 84-96553-06-X.
  3. ^ Salewski, Volker, Herbert Stark and Bernd Leisler (2009) Olivaceous Warblers in Southeast Morocco British Birds 102(3): 116-21
  • Fregin, S., M. Haase, U. Olsson, and P. Alström. 2009. Multi-locus phylogeny of the family Acrocephalidae (Aves: Passeriformes) - the traditional taxonomy overthrown. Molecular Phylogenetics and Evolution 52: 866–878.
  • Sangster, G., J.M. Collinson, P.-A. Crochet, A.G. Knox, D.T. Parkin, L. Svensson, and S.C. Votier. 2011. Taxonomic recommendations for British birds: seventh report. Ibis 153: 883–892.