Nesting biology of the Pacific Eider Somateria mollissima v-nigrum on the Western Chukotka
O. D. PROKOPENKO, D. A. BARYKINA, D. V. SOLOVYEVA
Institute for Biological Problems of the North, FEB RAS, Magadan, Russia
Keywords: breeding season phenology, nesting density, nest success, clutch size, egg size, meteorological predictors, Chaun Bay
Abstract
The first data on the breeding biology of the Pacific Eider (Somateria mollissima v-nigrum) in the Asia were obtained using the example of the nesting population in the Apapelgin River (Western Chukotka). From 2018 to 2024, research was conducted to assess nesting density, phenology, and reproductive parameters of the eider. A total of 1,291 nests of this species were examined. The study presents data on the key parameters of the investigated nesting population: eiders predominantly nested in coastal lowlands rich in lakes, known as “laida.” The average nesting density was 26.8 ± 2.3 nests/kmІ, showing a declining trend over the years (RІ = 0.7). The average clutch size was 4.7 ± 0.1 eggs. The onset of egg-laying was influenced by the rate of snowmelt and the average temperatures during the last decade of May. The apparent nesting success across all years was 33.4 %, and the cumulative Mayfield Nest Success (MNS) estimate during the egg-laying and incubation periods was 0.37 ± 0.14. The egg volume in clutches decreased over the study period and was influenced by weather conditions at the beginning of the nesting season, the date of egg-laying, and clutch size. The obtained data were analyzed in comparison with similar data on nesting populations from the American continent.
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