Feeding ecology of the slaty-backed gull (Larus schistisagus) on Kuril’skoe Lake (southern Kamchatka Peninsula)

Abstract

Data on the feeding of the slaty-backed gull (Larus schistisagus) nesting at the largest Asian red salmon spawning site—Kuril’skoe Lake (southern Kamchatka)—are analyzed. The seasonal dynamics of the qualitative composition of the diet of nesting slaty-backed gulls was determined. The data on the diet obtained for the lake and coastal nesting populations are compared. Typical colonies of slaty-backed gulls are situated no farther than 3 km from the sea. The birds use the following foraging strategies: (1) foraging near the colony; (2) Pacific salmon (Oncorhynchus) preference; and (3) feeding in the littoral zone. Red salmon is the basic component of the gull trophic chain in the lake ecosystem. The seasonal changes in the typical foraging strategies of slaty-backed gulls observed on Kuril’skoe Lake depended on the state of food reserves. Foraging flights of gulls for the red salmon did not exceed 5 km, whereas the use of littoral food was minimal. In addition, red salmon gurry was also the mass food for gulls, which was collected at a distance of approximately 40 km from the colony.