Marsh Warbler
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| Acrocephalus palustris (Bechstein, 1798) |
The Marsh Warbler, Acrocephalus palustris, is an Old World warbler in the genus Acrocephalus. It breeds in temperate Europe and western Asia. It is migratory, wintering in south east Africa. It does not breed in the Iberian peninsula, and in England it is scarce and declining, with the former main centre of population in Worcestershire now extinct.
This small passerine bird is a species found in fairly tall rank vegetation in marshes or by rivers. 3-6 eggs are laid in a nest in reeds or low vegetation. This species is usually monogamous (Leisler & Wink 2000).
This is a medium-sized warbler. The adult has a plain brown back and pale underparts. It can be confused with the Reed Warbler, but is greyer on the back, the forehead is less flattened and the bill is less strong and pointed. The sexes are identical, as with most warblers, but young birds are yellower below.
The habitat is different from the reed beds favoured by the Reed Warbler. Like most warblers, the Marsh Warbler is insectivorous, but will take other small food items including berries.
In the breeding season, the best identification feature is the song, which is high and fast, and consists almost entirely of mimicry of other birds, punctuated with typically acrocephaline sqeaks and whistles. Dozens of different European and African bird calls have been identified in the song of this warbler.
[edit] Conservation
The reasons for the population decline of this species are not completely understood, but the fragmentation of habitat has been discussed in UK official documents of it Biodiversity Action Plan, a national program for protection of this declining species. Fragmentation is a generic term usually associated with land develoment patterns of an expanding human population. It is notable, however, that in continental Europe at least, the species in known to have a short breeding season (52-55 days: Leisler & Wink 2000) making it more vulnerable to climate change.
[edit] References
- BirdLife International (2004). Acrocephalus palustris. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006. Database entry includes justification for why this species is of least concern
- Leisler, B. & Wink, Michael (2000): Frequencies of multiple paternity in three Acrocephalus species (Aves: Sylviidae) with different mating systems (A. palustris, A. arundinaceus, A. paludicola). Ethology, Ecology & Evolution 12: 237-249. PDF fulltext
