Distribution of Sibling Species Yellow-legged Gull, Larus michahellis and Caspian Gull, Larus cachinnans (Charadriiformes, Laridae), on the Black Sea Coast

Distribution of sibling species Larus cachinnans (Pallas, 1811) and Larus michahellis (J. F. Naumann 1840) were studied on coast of the Black Sea. Originally, Larus michahellis breeds on seaside cliffs and rocky islets of the Southern part of the Black Sea and of the Crimean Peninsula. Having adapted to breeding on the roofs of buildings, this species is spread to the north along the seaside: to Novorossiysk on the eastern coast, to Constanta on the western one. Additionally, an isolated population of Larus cachinnans breeds on low-lying islands and sand spits mostly in the Northwestern Black Sea. Here, the species spreads on the seaside from Constanta northward to Karkinitian Bay. Further to the east, breeding populations of Caspian Gull are found on the Black Sea coast only at the southeastern edge of the Taman Peninsula to the south to Anapa. The coast of the Sea of Azov, adjacent to the northeastern part of the Black Sea, is densely populated by Larus cachinnans. Only in the southern part of the Sea of Azov, on the coast of the Kerch Peninsula, there is a small population of Larus michahellis.