Differential stopover of blackcap (Sylvia atricapilla) by sex and age at Eilat, Israel

We studied the stopover ecology of Blackcaps in Eilat, Israel, at the northern edge of the Saharan desert crossing. We investigated the Blackcaps with regard to differential migration by sex or age class in spring and autumn, and the stopover site in spring and autumn were compared. Using data from 1984 to 2003, we studied stopover length and fat deposition patterns differentiated by sex. In spring, Blackcap females remained in Eilat significantly longer than males. This suggests that males maintain a migration strategy of time-minimization, while females place more importance on energy-maximization. This difference is probably due to upcoming reproductive roles at the breeding grounds.