SEEN - SE European Bird Migration Network
Studies of directional preferences of Chiffchaff (Phylloscopus collybita) and Willow Warbler (Phylloscopus trochilus) during autumn migration in Kalimok (Bulgaria).

Karolina Adamska1, Monika Filar2
Bird Migration Research Station, University of GdaƄsk, Przebendowo, 84-210 Choczewo, Poland 1, 2

Migratory orientation of the Chiffchaff (Phylloscopus collybita) and the Willow Warbler (Phylloscopus trochilus) investigated with cage experiments during autumn migration are presented in this study. Tests in the Busse?s cage were applied to determine their directional preferences. All orientation data were collected at Kalimok Ringing Station (Northern Bulgaria) in October 2006. Totally, 246 orientation tests including 218 tests of the Chiffchaff and 28 of the Willow Warbler were performed. Tested species showed similar distribution of headings. SSE direction was observed and also two northern directions NNE and ENE were noted. However in the Willow Warbler SSE direction dominated, while the Chiffchaff?s distribution of directions was more dispersed. Additionally the latter displayed tendency towards SSW as well. 24 individuals of Chiffchaffs, randomly selected were tested twice. During these analyses we found that birds tested for the second time showed clearer pattern of preferred headings. Moreover proportion of ?northern? directions (opposite to the standard direction during autumn migration) decreased from 54% to 28%. This could suggest that stress connected with specific conditions of orientation cage tests might have influence on bird behaviour during the test. That is why during the following test, effect of that factor discreased.

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