BREEDING BIOLOGY OF THE PARAKEET AUKLET (CYCLORRHYNCHUS PSITTACULA) ON TALAN ISLAND (NORTHERN PART OF THE SEA OF OKHOTSK)

摘要

Biology of reproduction of parakeet auklet was studied in 1989-2012 on Talan Island located in Tauiskaya Bay, the Sea of Okhotsk. 111 2008, its population amounted to 3000 individuals; 70% of the birds nested on the western slope; the average density of nesting was 0.018 pairs/m(2). Most of the nests were recorded along the slope base (5-20 m a.s.l.) while the largest density there was 0.035 pairs/m(2). Egg laying began from 4 June to 14 June (the mean annual data is 8 June). The latest date of egg laying (12-14 June) was observed in 1995, 1999 and 2001 related to ice crushing nearby the island. Hatching in different years started on 9-19 July and ended in late July-early August. The mass of hatchlings was 20-33 g (average is 27.9). In different years, the maximum weight of 22-29-day-old nestlings was 173-263 g. By the time of fledging, their mass decreased down 168-252 g, while the daily increase in weight, when birds stayed in the nests, was 4.06-6.47g in different years. The wing length of fledglings varied from 103 to 140 mm (on the average, 123.5 mm) Young (31-35-day-old) birds left the island in mid-August - the first decade of September. The reproductive success of parakeet auklets varied from 0 to 83.3% (44.3) and was mainly determined by the survival of chicks at different stages of their development. The main limiting factor of the reproductive success is the reduction of forage availability and abundance due to unfavorable weather conditions.