engleski

Morphological variation of European Reed Warblers across a migratory divide.

A migratory divide is a zone of contact between two parapatric populations migrating to two disparate directions. Ringing recoveries of Reed Warblers (Acrocephalus scirpaceus) suggest that such a migratory divide exists in central Europe separating populations using SW and SE migratory directions when heading for their winter quarters in Africa. We studied morphological variation of Reed Warblers at 11 study sites stretching from Spain and Wales in the west to Lithuania in the north and Romania and Bulgaria in the east. Only data for adult breeding birds measured in 2003 and 2004 were included in our analyses. Body size (expressed as an index from PCA of three body measurements) increased with latitude and longitude. Even a stronger correlation of body size with both longitude and latitude was found for breeding populations with known SW migratory directions, whereas no such a trend was apparent for populations with SE migratory direction. Hungarian Reed Warblers differed from other populations by longer foot spans. The geographical patterns of Reed Warbler morphology will be discussed in light of the species’ migratory divide and general ecogeographical gradients in birds (Bergmann’ s and Seebohm’ s rules).

Reed Warbler Acrocephalus scirpaceus; migratory divide; morphological variation

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