干旱区生态环境知识资源中心

Studies conducted within the framework of the EURING Swallow Project in the Mediterranean area pointed out that the fattening of Barn Swallows is dependent on the distance they need to cover to pass over ecological barriers, such as sea and desert via their migration route. Our study was conducted at inland sites and we analysed the data in comparison to results previously obtained in the western Mediterraneum. Barn Swallows were captured at two roosting sites in Hungary: Ocsa peat bog and Izsak, at Lake Kolon between 2000-2002 with tape-luring set up each day one and a half hours before sunset. During the study period 7000 adult and 36000 juvenile Barn Swallows were caught. Wing length, 3rd primary length, tail length, body mass and fat score were measured for all adults and for the first 100 juveniles birds each night. Based on the dynamics of fat accumulation the study period was separated to a post-breeding, a transitional and a pre-migratory phase. The observed pattern between years and sites were similar, and there were recaptures during the same autumn between the two roosting sites (60 km from each other) to north and to south direction as well. Our results can not exclude one of the two alternative hypotheses on Barn Swallow migration strategy that is: (1) Barn Swallows build up their fat reserves in Hungary and afterwards they maintain it while slowly reaching the ecological barriers, and (2) Barn Swallows capable of a non-stop migration from Hungary to the southern edge of the Sahara. Efforts to find important refuelling sites in the eastern Mediterranean are needed to support any of the hypotheses.