About Black Sea population of the Eider. - O.A. Yaremchenko, K.I. Rybachuk. - Berkut. 8 (2). 1999. P. 155-159.
Nesting of the Eider was recorded in the territory of the Black Sea Biosphere Reserve (South of Ukraine) in the 1975. Two nests was found on the Dolgiy island in the Yagorlitskiy bay of the Black Sea (Ardamatskaya, 1981). Number of eiders was increased during the study period (Table 1). Number increasing alternated with short-term recessions. At present the Black Sea population of the species makes about 1800 breeding pairs. The main kernel of population is situated on the Dolgiy and Krugliy islands. 1600 pairs nest here. A part of the population was moved to east of the Reserve. The species occupied the Orlov, New, Egyptian islands in the Tendrovskiy and Yagorlitskiy bays. 220 nests were counted here. Some changes in breeding biology of the Eider population were watched. Birds began to lay eggs earlier, than in first years; clutch size decreased, variation of egg numbers extended; the volume of eggs increased (on average on 1,42). Now egg laying begins in end of March - beginning of April, chicks appear in end of April - beginning of May. Average clutch size in a year makes to 5,3. The breeding success of the Eider fluctuates as a rule from 60 to 98 %. The main factors of influence on the breeding success are following: high level of water on the islands and predation of the Yellow-legged Gull. The Eider population has progressive development in the South of Ukraine. Its present condition does not cause fears. [Russian].
Key words: Eider, Black Sea, distribution, number, breeding, phenology, clutch, egg, breeding success.
Address: O.A. Yaremchenko, Black Sea Biosphere Reserve, Lermontova str. 1, 75600 Golaya Pristan, Kherson region, Ukraine.