BRENT GEESE (BRANTA BERNICLA) BREEDING ASSOCIATIONS WITH POMARINE SKUAS (STERCORARIUS POMRINUS) IN THE MAINLAND TUNDRA

摘要

This communication is based on data collected in 2000-2007, 2012 and 2014 in the vicinities of Medusa Bay (73 degrees 21'N, 80 degrees 32'E); and in 2002 in the Uboynaya River mouth (73 degrees 37'N, 82 degrees 10'E), north-west of Taimyr Peninsula. In the years when the lemming numbers were high, brent geese were capable of breeding not only near nests of the Snowy Owl and the Rough-legged Buzzard, but sparsely also in the mainland tundra, often without any protection. Some of such nests successfully incubated until hatching. A considerable proportion of these dispersed nests appears to have been associated with a breeding pair of the Pomarine Skua. These skuas were capable of scaring away the arctic fox, the main tundra predator, to a distance of more than 500 m from their nests. Brent geese that bred within this distance from a skua nest thus received protection against arctic foxes. However, for an unknown reason, geese failed to show a tendency to placing their nests closer to pomarine skua nests. The mean distance from geese nests to the nearest pomarine skua nests or centers of their territories amounted to 2/3 of the mean distance between the nests (or territory centers) of pomatine skuas. This relation turned out to be quite stable between years and in different tundra areas.