Foraging patterns of northern fulmars in Alaska inferred from fatty acid signature analysis

Abstract

Diets of Northern Fulmars (Fulmarus glacialis) in the North Pacific are poorly known, and thus relationships of fulmars to supporting food webs and their potential sensitivity to ecosystem variability, such as that driven by a changing climate, also are uncertain. I employed a new technique, fatty acid (FA) signature analysis, to examine dietary differences among fulmars at three colonies in Alaska. I predicted that 1) signatures of adipose tissue and stomach oils would differ because the time scale each depot reflects differ and/or because adipose tissue FAs may be influenced by predator metabolism, while stomach oil FAs may be influenced by differential uptake; 2) fulmar diets would differ between colonies located in distinct oceanographic settings, which create unique habitats for prey assemblages; 3) diets would differ temporally within colonies because of inter-annual variability in the physical environment resulting in variation of prey FA signatures; and 4) diets of adult fulmars and their chicks would be similar because they feed by regurgitation. I found that FA signatures of adipose tissue were significantly different than those of stomach oil; there were conspicuous spatial and temporal differences in adipose tissue signatures; but diets of adults may differ from those of chicks.