AVIAN PREDATION AT PENGUIN COLONIES ON KING GEORGE ISLAND, ANTARCTICA

摘要

Predation at seven colonies that varied in size from 10 to hundreds of breeding pairs of Adelie (Pygoscelis adeliae) and Gentoo (P. papua) penguins was observed from a blind at King George Island, Antarctic Peninsula, from 21 Dec. 1993 to 3 Feb. 1994. We observed the colonies for 96 h to record foraging by Brown Skuas (Catharacta lonnbergi), Kelp Gulls (Lams dominicanus), and Giant Petrels (Macronectes giganteus) during the early chick through creche phase of the penguin breeding cycle. Activity rates by predators varied little with time of day or time of season for skuas and petrels. Kelp Gulls, however, showed significant variation in rates with time of season. Total activity and search rates were significantly higher for each predator species at larger versus smaller colonies. In addition, attempted predation and predation by skuas on penguin chicks were significantly higher, and from 4.1-7.9x more frequent, at colony edges rather than the center. Larger colonies probably receive greater attention by predators because of the larger number of prey, and by their greater circumference and edge area. Low breeding success by penguins in small colonies appeared to be partially attributed to predation losses, although predation rates were low. Penguin reproductive success may be significantly influenced by colony size and by the number and kinds of predators attending them.