Migratory stopovers of passerines in an oasis at the crossroads of the African and Indian flyways

We studied migratory stopovers of nocturnal passerine migrants migrating between the Urals and Siberia and the Near East and Africa (five species) and between European Russia and the Indian subcontinent (two species) in an oasis in the arid belt of the northwestern edge of western Central Asia. In autumn, fuel loads of Blyth's Reed Warblers Acrocephalus dumetorum before their desert crossing were much greater than in Palaearctic‐African migrants, which face a much narrower barrier, and also greater than in conspecifics captured during and after the desert crossing. However, another Indian migrant, the Redbreasted Flycatcher Ficedula parva, had low average fuel stores. In spring, Blyth's Reed Warblers carried less fuel than in autumn, and less than African migrants such as Garden Warblers Sylvia borin in spring. This suggests that the arid belt of western Central Asia is a serious ecological barrier for Palaearctic‐Indian passerine migrants in autumn, but much less of one in spring. Palaearctic‐African migrants which make a detour around this barrier to the northwest and migrate north of the Caspian Sea do not need large fuel stores like those they deposit before crossing the Sahara.