Breeding of waders (Charadrii) and Brent Geese Branta bernicla bernicla at Pronchishcheva Lake, northeastern Taimyr, Russia, in a peak and a decreasing lemming year

During summer 1991, lemmings occurred at high densities in Arctic tundra at Pronchishcheva Lake in the northeastern Taimyr Peninsula, whereas, in 1992, lemming densities were substantially lower and decreased further during the summer. In 1991, avian predators such as Snowy Owls Nyctea scandiaca, gulls and skuas bred well; Arctic foxes Alopex lagopus were rarely observed in the study area but bred in the immediate vicinity. In both years there was a late thaw, but this did not deter breeding by birds. The insect food supply for waders showed similar patterns of abundance in both years. In 1991, 73 nests of nine species of wader were found within a 14-km2 study area, and Dark-bellied Brent Geese Branta bernicla bernicla nested in association with Snowy Owls. The overall density of wader nests was estimated to be 7 per km2. Clutches disappeared at only two wader nests and no Brent Goose nests, and the Mayfield estimate of the daily probability of predation for waders was 0.0022. In contrast, the daily probability of predation was 0.20 in 1992, when there was a similar breeding density of waders. Arctic foxes were seen searching for food daily within the study area, and fox droppings were found associated with nests taken by predators. The predicted scenarios for peak and decreasing lemming years (the Roselaar-Summers hypothesis), i.e. low predation and high nest success in the peak year and high predation and low nest success in the decreasing year, therefore occurred.