Stopover ecology of migratory Sedge Warblers (Acrocephalus schoenobaenus) at Eilat, Israel

Abstract

Migrating Sedge Warblers Acrocephalus schoenobaenus were captured in Eilat, Israel, during their spring and autumn migration. Data on spring and autumn body masses, their interannual variation and the pattern of fuel accumulation were analysed. Body mass and body condition index significantly varied between the years of study in spring but not in autumn. This may be due to birds over-flying the area, but loop migration might also be involved. Sedge Warblers gain mass in Eilat, both in spring and in autumn. Birds in poor initial condition and those stopping over for a longer period gained more body mass faster. In spring, but not in autumn, the progress of the season was another important factor: late birds gained more body mass. The average rate of body mass gain was 0.179g day-1 ± SE = 0.026. This suggests that Eilat is an important staging area for Sedge Warblers in spring and to a smaller extent in autumn.