Stopover strategies of Eurasian Blackcaps (Sylvia atricapilla) during the post-fledging period in western Hungary

摘要

Stopover strategies of the Eurasian Blackcap (Sylvia atricapilla) during the post-fledging period were studied at Tomord, western Hungary, between 1998 and 2015. Capture data of juveniles and adults were pooled for both sexes, and recapture rate, stopover length and fat deposition patterns were analyzed. During stopover, males and females did not differ significantly in stopover length, total change in body mass, proportion or rate of body mass change, or change in fat score. Among all recaptures, an overall significant positive correlation was recognized between mass deposition rate (g/day) and departure body mass. According to our results, both males and females use a time-minimization migration strategy in autumn. The benefit of this strategy might be that it favors early arrival in the overwintering areas, before competitors. The individuals arriving earlier at wintering sites might obtain higher-quality territories and achieve higher winter survival. This might he particularly important in populations that are increasing, which is the case for the Blackcap. Our data support the idea that most Blackcaps were using the study site at Tomord as a stopover area, but only a small number of them were using it as a site specifically to fatten up.