Great Reed Warbler - Distribution and Ecology

Distribution and Ecology

A. arundinaceus breeds in Europe and westernmost temperate Asia. It does not breed in Great Britain, but is a regular visitor. Its population has in recent decades increased around the eastern Baltic, while it has become rarer at the western end of its range. It a is migratory bird, wintering in tropical Africa. This bird migrates north at a rather late date, and some birds remain in their winter quarters until the end of April.

While there are no subspecies of this bird, mtDNA haplotype data indicates that during the last glacial period there were two allopatric populations of A. arundinaceus. The Great Reed Warblers in southwestern and southeastern Europe were at that time apparently separated by the Vistulian-Würm ice sheets and the surrounding barren lands. Though the data is insufficient to robustly infer a date for this separation, it suggests the populations became separated around 80,000 years ago – coincident with the first major advance of the ice sheets. The populations must have expanded their range again at the start of the Holocene about 13,000 years ago, but even today the western birds winter in the west and the eastern birds in the east of tropical Africa.

This passerine bird is found in large reed beds, often with some bushes. On their breeding grounds, they are territorial. In their winter quarters, they are frequently found in large groups, and may occupy a reed bed to the exclusion of other birds. Like most warblers, it is insectivorous, but it will take other prey items of small size, including vertebrates such as tadpoles.

The Great Reed Warbler undergoes marked long-term population fluctuations, and it is able to expand its range quickly when new habitat becomes available, this common and widespread bird is considered a Species of Least Concern by the IUCN.