PHILOPATRY, MATE FIDELITY, AND NEST-SITE FIDELITY FOR SOUTH POLAR SKUAS STERCORARIUS MACCORMICKI AT THE VESTFOLD HILLS, EAST ANTARCTICA

Antarctica experiences continual spatial and temporal expansions in human activities, but information to understand how resident species may be impacted is usually inadequate. We analysed resights of South Polar Skuas Stercorarius maccormicki that were individually marked with leg rings during 1999-2004 to compare breeding behaviours such as philopatry, adult mate fidelity, and site fidelity in the Vestfold Hills population, East Antarctica, with other regions. Despite their impressive dispersal capabilities, philopatry for birds resighted in the study area was within 4 km of the natal nest, and adult nest-fidelity was within 1 km of a previous nest site. Such faithfulness to site, combined with a life expectancy of > 25 years, indicates that displacement of returning adults and offspring from established breeding habitat may be a slow process, perhaps at generational timescales. Mate fidelity for birds ringed as breeding pairs exceeded 10 years, with individuals of pairs who failed to return or skipped breeding for single or multiple seasons being readily replaced. Resights of marked individuals also showed the Vestfold Hills receives individual skuas from distant sources; hence, we can learn more about the role of this predatory, highly migratory species in the spread of disease across landscapes and between seabird species. This study extends our understanding of skua ecology and their high nest-site and mate fidelity. Findings suggesting that their capacity to relocate in response to human disturbance may be limited.