Seabird research at Cape Shirreff, Livingston Island, Antarctica, 2004/05

The eighth complete consecutive season of data collection at Cape Shirreff has enabled us to examine trends in penguin population dynamics, as well as inter-annual variation in penguin diet, and foraging behaviour. The chinstrap breeding population at Cape Shirreff has continued to decline over the past six years, and is at its lowest size in the past eight years of study, and fledging success was poor compared to earlier years of study. The gentoo breeding population, in contrast, has remained relatively stable and had similar fledging success in 2004as the long-term mean. Fledging weights of both species decreased from last year, and were the lowest average weights seen over nine years. The diet of both chinstrap and gentoo penguins contained primarily adult female Antarctic krill, peaking in the 46-50mm range, continuing a four year trend of increasing proportions of female krill and increasingly larger krill. The diet of both species contained less fish than in other years on average. Total chick meal mass was larger for chinstrap penguins compared to the past seven years of study, primarily in the digested portion of the meal. The interpretation of these diet patterns may be aided by analysis of foraging location and diving behaviour data.