Data from: Partial migration in the Mediterranean storm petrel Hydrobates pelagicus melitensis

Studying the migration routes and wintering areas of seabirds is crucial to understanding their ecology and to inform conservation efforts. Here we present results of a tracking study carried out on the little-known Mediterranean Storm Petrel Hydrobates pelagicus melitensis. During the 2016 breeding season, Global Location Sensor (GLS) tags were deployed on birds at the largest Mediterranean colony: the islet of Filfla in the Maltese Archipelago. The devices were retrieved the following season, revealing hitherto unknown movements and wintering areas of this species. Most individuals remained in the Mediterranean throughout the year, with birds shifting westwards or remaining in the central Mediterranean during winter. However, one bird left the Mediterranean through the Strait of Gibraltar and wintered in the North Atlantic. Our results from GLS tracking, which are supported by data from ringed and recovered birds, point toward a system of partial migration with high inter-individual variation. This highlights the importance of trans-boundary marine protection for the conservation of vulnerable seabirds.