MICROSATELLITES IDENTIFY DEPREDATED WATERFOWL REMAINS FROM GLAUCOUS GULL STOMACHS

Prey remains can provide valuable sources of information regarding cau ses of predation and the species composition of a predator's diet. Unf ortunately, the highly degraded state of many prey samples from gastro intestinal tracts often precludes unambiguous identification. We descr ibe a procedure by which PCR amplification of taxonomically informativ e microsatellite loci were used to identify species of waterfowl preda ted by glaucous gulls (Larus hyperboreus). We found that one microsate llite locus unambiguously distinguished between species of the subfami ly Anserinae (whistling ducks, geese and swans) and those of the subfa mily Anatidae (all other ducks). An additional locus distinguished the remains of all geese and swan species known to nest on the Yukon-Kusk okwim delta in western Alaska. The study focused on two waterfowl spec ies which have experienced precipitous declines in population numbers: emperor geese (Chen canagica) and spectacled elders (Somateria fische ri). No evidence of predation on spectacled elders was observed. Twent y-six percent of all glaucous gull stomachs examined contained the rem ains of juvenile emperor geese.