title: Exploitation of inland-breeding Antarctic petrels by south polar skuas.
abstract: During the austral summer of 1996/1997 we studied south polar skuas at Svarthamaren, Dronning Maud Land, Antarctica, where the world's largest known colony of Antarctic petrels is found. Our censuses suggested approximately 250 full-grown skuas and 140,000 breeding pairs of petrels were present. During their breeding season, skuas did not visit the open sea at least 200 km from the site; they relied entirely on prey caught and scavenged from the petrel colony. Because the site is so isolated, we asked whether the prey (petrels) had swamped the predators (skuas), or whether there was evidence that predator numbers were limited by the size of the prey population. Particularly at the end of the petrel incubation period, we found a close correspondence between the energy required by adult skuas and their chicks, ascertained from time budget studies, and the rate at which petrel eggs disappeared from the colony. This suggests that, in this closed system, the predator population was limited by the prey population, and that predator swamping was not an advantage that petrels gained by nesting in this remote location.
authors.affiliation: Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK e-mail: mb10005@cus.cam.ac.uk, Tel.: +44-1223-336610, Fax: +44-1223-336676, , , , , , GB.
authors.forename: M L
authors.initials: ML
authors.lastname: Brooke
authors.affiliation: Percy FitzPatrick Institute, University of Cape Town, Rondebosch 7701, South Africa, , , , , , ZA.
authors.forename: D
authors.initials: D
authors.lastname: Keith
authors.affiliation: Norwegian Institute for Nature Research, Tungasletta 2, N-7005 Trondheim, Norway, , , , , , NO.
authors.forename: N
authors.initials: N
authors.lastname: Røv
keywords: Antarctica; Daily energy expenditure; Key words Predation rate; Predator swamping; Time budget