ИСТИНА

The dependence of nest survival in tundra-breeding waders on abundance and activity of potential predators their alternative prey (lemmings) were studied in 2011–2014 in the Low Arctic (SE Taimyr, 72°51' N, 106°04' E) and in 2015–2016 in the High Arctic (NW Taimyr, 73°21' N, 80°32' E). We used experiments with artificial nests to evaluate the impact of some other factors (but not actual bird nest survival). Automatic cameras were used for predator identification. Daily survival rates differed significantly in the study period and were extremely low in 2012 and 2015, the years of extremely low abundance of lemmings and very high activity of Arctic foxes. In these years, the Arctic fox was the only and very efficient predator of wader clutches. In the Low Arctic, avian predators (two species of skuas) nested in low numbers in all years; in all habitats their influence was minor compared to that of the Arctic fox, and negligible in the years of low abundance of lemmings. In the seasons with higher lemming abundance avian predators could have contributed to wader clutch predation, as indicated by differences in survival of clutches with different overhead concealment. In the High Arctic, the avian predators nested with relatively high density in 2016 (intermediate abundance of lemmings), and definitely played a certain role in nest predation, whereas the abundance and activity of Arctic foxes in the study area was extremely low. However, the majority of nests depredated by skuas in 2016 were artificial, and the nest success in waders was very high. Thus, the abundance of alternative prey and related abundance and activities of Arctic foxes had the strongest impact on wader nest survival both in the Low and High Arctic. The significance of the nest site selection in general and nest concealment in particular may be greater in areas with higher density of avian predators.