Migration strategies of the Yelkouan Shearwater Puffinus yelkouan

Although the Yelkouan Shearwater Puffinus yelkouan is listed as near threatened on the International Union for Conservation of Nature Red List, with many populations in serious decline, there is little detailed information on the location of its key foraging areas during the non-breeding season. To address this knowledge gap, adult Yelkouan Shearwaters at a breeding colony in Malta were fitted with geolocators in 2 consecutive years. Of the 13 birds tracked (two of which were tracked in both years), the majority (n = 10; 76.9 %) migrated in June–July to spend most of the non-breeding period in the Black Sea (n = 5), Aegean Sea (n = 2), Black and Aegean seas (n = 2), or Black and Adriatic seas (n = 1). The final three birds remained within the central Mediterranean area and did not move beyond 500 km of the breeding colony. There was considerable variation among individuals in terms of timing of the outward and return migrations, duration and location of periods of residency in different areas, and migration routes. However, migration patterns (including routes and areas visited) were very consistent in the two individuals tracked in consecutive years. All birds returned in November or December to waters closer to the breeding colony, concentrating between the North African coast and the southern Adriatic. This study has identified key areas during the non-breeding season for Yelkouan Shearwaters from Malta which are also likely to be important for other populations. Given the continuing decline of this species throughout its range, this information represents an essential step for improving international conservation efforts. At-sea threats in the wintering regions include by-catch in long-line and trawl fisheries, impacts of over-fishing, illegal hunting (particularly in Maltese waters), ingestion of plastics, pollution, and the potential impact of off-shore wind farms. These threats need to be addressed urgently in the areas identified by this study to prevent further declines.