Observations on the age structure of Kaniv colony of the Yellow-legged Gull (Larus cachinnans). - V.N. Grishchenko, E.D. Yablonovska-Grishchenko. - Berkut. 22 (1). 2013. - P. 44-47.
The colony is located on the concrete breakwater near Kaniv hydroelectric power station (49.46 N, 31.27 E). Till 2008, it was a largest colony of the Yellow-legged Gull on the Middle Dnieper. Later number of breeding birds sharply decreased. In 1997–2007, we ringed 3581 chicks by metal rings. In 2004–2005 and 2007–2008, numbers of rings in 68 breeding gulls were read (86 resightings) using scopes. Three birds were found during three seasons, 12 – during two seasons. More than two thirds of ringed gulls were 4 to 7 years old. Mean age of first breeding was 4,9 ± 0,2 years (n = 30). 13,3% from gulls bred for the first time were 3 years old, 23,3% – 4, 33,3% – 5, 20,0% – 6, 10,0% – 7. Observations in the colony have shown that there is the considerable emigration of gulls. Only about 5% of birds had rings although we ringed yearly from a half up to ¾ of all chicks. It was confirmed by recoveries. Three gulls from Kaniv were found in breeding colonies in Poland and Byelorussia. [Russian].
Key words: ringing, demography, age structure, age of first breeding, migration.
Address: V.N. Grishchenko, Kaniv Nature Reserve; Kaniv, 19000, Ukraine; e-mail: vgrishchenko@mail.ru.