MEPS 553:267-281 (2016)  -  DOI:

Consistency in migration strategies and habitat preferences of brown skuas over two winters, a decade apart

Ana P. B. Carneiro1,2,*, Andrea Manica1, Thomas A. Clay1,2, Janet R. D. Silk2, Michelle King2, Richard A. Phillips2

1Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
2British Antarctic Survey, Natural Environment Research Council, Madingley Road, High Cross, Cambridge CB3 0ET, UK
*Corresponding author:

ABSTRACT: At-sea movements and activity patterns of brown skuas Stercorarius antarcticus lonnbergi from South Georgia were analysed in 2 winters, a decade apart, to examine the degree of consistency in migration strategies and habitat preferences during the non-breeding and pre-laying exodus periods. Oceanographic habitat preferences of tracked skuas were determined using a robust model accounting for availability. At the population level, brown skuas were broadly consistent in their choice of wintering areas and habitat preferences, although the distribution extended farther east in 2012 than in 2002. Skuas preferred areas associated with static oceanography (bathymetric features) both during the non-breeding and pre-laying periods, which may explain the consistency between years in habitat use. There was no significant effect of year on departure dates from South Georgia, but birds returned earlier to the colony in 2002. Migration schedules varied according to breeding status, with failed birds departing earlier than birds that bred successfully. Although failed birds travelled farther from the colony, there was little variation in dates of return. In general the timing of movements was similar between sexes, but females were more likely than males to engage in a pre-laying exodus. Brown skuas spent a much higher proportion of time sitting on the water than other seabirds during both the non-breeding and pre-laying exodus periods, and the number of flight bouts per day was surprisingly low. The selection of static features by brown skuas may indicate that skuas may have less flexibility to track environmental changes than species that use dynamic cues.

KEY WORDS: Annual variability · Biologging · GAMs · Geolocation · GLS · Habitat selection · Modelling · Seabird

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Cite this article as: Carneiro APB, Manica A, Clay TA, Silk JRD, King M, Phillips RA (2016) Consistency in migration strategies and habitat preferences of brown skuas over two winters, a decade apart. Mar Ecol Prog Ser 553:267-281.

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