Census of breeding avifauna and the status of Audouin’s Gull ( Ichthyaetus audouinii ) along the eastern Mediterranean coast of Turkey

We conducted the first extensive breeding bird and habitat survey across 21 islands and islets spanning 600 km of the eastern Mediterranean coastline of Turkey in 2016. Eight of the 21 islands hosted breeding colonies of at least one of three seabird species: European Shag ( Gulosus aristotelis ) on four islands and two coastal cliffs with 9–29 breeding pairs, Yellow-legged Gull ( Larus michahellis ) on eight islands with 145–175 breeding pairs, and Audouin’s Gull ( Ichthyaetus audouinii ) on one island with 6–7 breeding pairs. Two Scopoli’s Shearwaters ( Calonectris diomedea ) were also observed during the coastal cruise, but no conclusive breeding evidence was collected. The single Audouin’s Gull breeding colony alternated between two nearby islands, and the breeding population fluctuated between 6–10 pairs between 2016 and 2023. Comparisons between previous population estimates and the present survey indicated that the Audouin’s Gull breeding colony has suffered a ~65–80% population loss in the last five decades. Habitat surveys revealed that 13 islands had some vegetation cover. Bushes were the dominant vegetation and hosted the highest seabird nest abundance. However, the highest seabird nest density was observed in herbaceous vegetation, which had only marginal coverage on the islands, potentially due to overgrazing by introduced rabbits and goats. Furthermore, surveys revealed occasional mortality of gull eggs, chicks, and adults as well as anthropogenic pressures on seabird breeding habitats such as uncontrolled recreational use and introduced mammals. The islands also hosted 15 other breeding bird species, including large populations of Alpine Swift ( Tachymarptis melba , ~270 pairs) as well as several raptor species. Overall, our results indicated that there is significant seabird breeding activity in the eastern Mediterranean coastline of Turkey and an urgent need for ecosystem management to protect the habitat quality of these islands for seabird breeding populations.