SEEN - SE European Bird Migration Network
Directions of autumn migration of three passerine trans-Saharan migrants in Bulgaria: results from orientation cage experiments
Mihaela Ilieva, Pavel Zehtindjiev
Institute of Zoology, Bulgarian Academy of Sciences, Bulgaria

Data for directional preferences of certain species and populations from the Balkan Peninsula are scarce. During the autumns of 2001, 2003 and 2004, we performed orientation experiments to examine the migratory directions of three species of trans-Saharan migrants, i.e. the Sedge Warbler (Acrocephalus schoenobaenus), Great Reed Warbler (A. arundinaceus) and Willow Warbler (Phylloscopus trochilus). Using two types of cages, Emlen funnels and Busse cages, 624 birds of these species were tested at Kalimok Field Station (41o00’N) 26o26’E, NE Bulgaria). The distribution of the directions in the three species showed bimodality, with most of the birds directed in SE or SW. Nevertheless, considerable proportions of Great Reed Warblers and Willow Warblers exhibited SSE and SSW-SW directions, respectively, while almost equal numbers of Sedge Warblers were directed SE and SW. The variations of the directionality within the species studied correlated with morphometric traits; this may indicate migratory preferences of different populations. The results obtained support the hypothesis for simultaneous passage of populations with different migratory directions through the territory of the Balkan Peninsula.
Created by Pronetix 2006