Transactions
of the Azov-Black Sea Ornithological Station
Decrease of numbers of the Yellow-legged Gull Larus michahellis J. F. Naumann on the Crimean Peninsula at the frontier of the XX‑XXI centuries
A. N. Tsvelykh
It was recently found out that the Caspian Gull Larus cachinnans does not breed on coastal cliffs of the Crimea, but its sibling species – Yellow-legged Gull Larus michahellis (Tsvelykh, 2016). It is obvious that previously collected data on the biology and abundance of gulls nesting in rocky habitats of the Crimean coast should be attributed to the latter species. Analysis of specimens of museum collections, published photographs and old publications showed that the Yellow-legged Gull breeds on the seaside cliffs of the Crimean peninsula long ago, at least since the beginning of the 20th century, and has not appeared here in recent times.
The results of counts in the significantly remote settlements of Larus michahellis in the Crimea showed that at the turn of the 1990s and 2000s there was a significant two up to threefold decrease of its number. On the coasts of the Heraclean peninsula between capes Khersones and Fiolent, in 1994 about 100 pairs of gulls bred and in 2002 only 32 pairs were registered here. In 1992 the number of gulls nesting on the rocky sea coast near mount Opuk was 25‑30 pairs, and by 1999 it decreased to 11-14 pairs. On the coast of Cape Kazantip in 1992, 10-15 pairs of gulls bred, and by 2005 there were no more than 5-7 pairs. During the same period (1992-2005), the number of gulls nesting on the seacoast of the Karadag Nature Reserve decreased from 60 up to 25 pairs. According to the analysis of published data of regular long-term surveys of the Yellow-legged Gull in the Karadag Nature Reserve, the number of the species regularly and significantly (r = –0,740, p < 0,001) decreased since the 1980s, and by the early 2000s it reached a minimum. Using the equation received from these data and information on the total number of the species in the Crimea in the early 2000s, the number of Larus michahellis in the Crimea in different years was estimated. For example, in 1980 number of the species was approximately 800 pairs, in 1990 – 530 pairs, and in 2000 – 250 pairs.
References:
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