Potential Changes in Autumn Migration Abundance and Phenology of Soaring Birds at an Important Migration Bottleneck in Southern Spain

The region of the Strait of Gibraltar, located between southernmost Spain and northern Morocco, is an important migration bottleneck for raptors and other soaring birds migrating from western Europe to winter in Africa. It is here that the shortest distance between continental Europe and North Africa is found, so the region acts as an obligatory crossing point for the majority of soaring birds migrating from western Europe. The Strait has experienced changes in climate and other abiotic conditions such that temperatures have warmed and the number of days during the migration period with unfavorable winds for crossing the Strait are increasing. This has resulted in some species delaying migration, others advancing migration dates, and still others wintering in southern Spain. As part of a National Science Foundation International Research Experience for Students project, we used data collected from a long-term, standardized monitoring program at this important migration bottleneck to examine potential changes in autumnal migration abundance and phenology of raptors. We compared current migration timing and volume to long-term data sets from 1976-1977 and from 1999-2024. Our poster discusses current trends and their implications for migrating birds during a time of regional climate change at this important migration site.