Fatty acid signatures as indicators of diet in great skuas Stercorarius skua, Shetland

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 319:297-310 (2006) - doi:10.3354/meps319297 Fatty acid signatures as indicators of diet in great skuas Stercorarius skua, Shetland Anne Käkelä1, Jonathan Crane2, Stephen C. Votier2, Robert W. Furness2, Reijo Käkelä1,* 1Department of Biology, University of Joensuu, PO Box 111, 80101 Joensuu, Finland 2Institute of Biomedical and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK *Corresponding author. Email: reijo.kakela@joensuu.fi ABSTRACT: Fatty acid signatures (FAS) were determined in plasma and adipose tissue of great skuas Stercorarius skua from Shetland in order to test the applicability of this biomarker in estimating diets of wild scavenging seabirds. The plasma FAS were compared with those of captive herring gulls Larus argentatus, which were fed typical Northeast Atlantic demersal and pelagic fish. The individual fatty acids that showed the largest proportional changes in FAS due to changes of dietary fish in herring gulls also varied the most in wild great skuas, suggesting a dietary origin of these changes in FAS. Thus, great skuas that had recently been feeding largely on a demersal or terrestrial diet were distinguished from individuals feeding mainly on a pelagic diet. Pronounced variation in the plasma FAS of great skuas suggests either very flexible feeding behaviour or individual dietary specialisation, which concurs with previous studies based on pellets. Individuals that regurgitated pellets consisting only of demersal fish, bird or rabbit showed larger values of a specific polyunsaturated fatty acid ratio (20:4n-6/18:3n-3+18:4n-3+20:5n-3) than birds whose pellets also contained remains of pelagic fish. Although pellet data showed a clear dominance of demersal fish in the summer diet of the great skua, the large proportions of long-chain monounsaturated fatty acids (e.g. 20:1n-9 and 22:1n-11) in adipose tissue of the great skua suggest that a considerable part of fat accumulated outside the breeding season comes from fatty pelagic fish. KEY WORDS: Adipose tissue · Fatty acid signatures · Fishery discards · Foraging ecology · Great skua · Plasma · Seabirds · Shetland Full text in pdf format PreviousExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 319. Online publication date: August 18, 2006 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2006 Inter-Research.