SEASONAL PATTERNS IN A MEDITERRANEAN BIRD COMMUNITY COMPOSED OF TRANSIENT, WINTERING AND RESIDENT PASSERINES

Fifteen sylviid and 9 turdid species inhabited a study site within a Mediterranean scrub in Israel: one yearlong resident species of each family, 1 sylviid and 3 turdid winter residents and 18 transients. Variations in bird abundance followed those of their resources' abundance such that the greatest biomass of Sylviidae occurred in spring, of Turdidae in winter, and the lowest biomass for both occurred in summer. Disparity between spring and autumn in total biomass of both groups associated with similarity between these seasons in each group's diversity, the strong temporal segregation between closely similar species and between migrants and closely similar residents at the time of young-feeding, and the low overall temporal overlap between species in spring, accentuated amongst morphologically similar species and partly resulting from the species' geographical segregation in Africa, all bring about ecological segregation in spring. In autumn resource levels and the site's location with regard to both distance from origin and desert-crossing, make it unattractive to migrants, which are then either spaced out more than in spring or skip the spring-utilized stopover sites.