SEEN - SE European Bird Migration Network
Orientation tests' results as a source data for analysis of migration strategy

Agnieszka Ożarowska
Bird Migration Research Station, University of Gdańsk, Przebendowo, 84-210 Choczewo, Poland

The Blackcap (Sylvia atricapilla) is one of the species showing complex migration system resulting from, among others, high population differentiation. These populations not only differ in the location of wintering quarters but also in migration strategy. The species is one of the most common used in orientation studies as well. All tested birds were caught with mist-nets, ringed and standard measurements were taken that included also fat-scoring. The blackcaps were tested in orientation cages following procedures proposed by Busse (1995). Material was collected during autumn migration season at several ringing stations: Bukowo (N Poland), Kaliszany (S Poland), Carpatica (S Poland), Arosio (N Italy), Cernek (N Turkey), Akyatan (S Turkey), Dhleil (Jordan). Different locations of these stations on the species migration flyways enabled to find some site specific characteristics of the Blackcap migration strategy. The analysis of migrational direction distributions at each of these stations showed high differentiation. At each location at least two main migrational axes could be determined. The fat score of the individuals showing distinguished migrational directions was analysed. The fat-score distribution in relation to migrational direction showed local characteristics of this phenomenon at each location along the migratory route of the species. The very interesting pattern was found at Arosio ringing station. This station location is a very special one as it covers both ? wintering grounds of the species as well as a stop-over place for the populations heading towards African winter quarters. The results showed two main migrational directions at this station and individuals representing these directions differed in the fat-score distribution. This could suggest different migration strategy of the Blackcap populations that winter within this region and other that are long-distance migrants heading towards African winter quarters.

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