Dominance behaviour, body weight and fat variations, and partial migration in European blackbirds Turdus merula

摘要: A partially migratory population of European blackbirds Turdus merula was studied in central Europe during the non-breeding season. Body weight and amount subcutaneous fat deposits showed seasonal variations typical for each age sex category. Juveniles were fattest autumn spring both juveniles females lost body mid-winter. Adults males reached their maximum These findings together with data from Schwabl (1983) suggest that constitute main fraction those birds migrating area autumn. In winter mainly adults have access to food resources. patterns may be regulated by dominance behaviour, since are usually dominant over throughout Subordinate stay probably suffer a higher mortality but advantage early breeding.