Foraging Behavior and Demography of Pygoscelis Penguins

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Seabird research conducted at Admiralty Bay, King George Island in the Antarctic Peninsula region has documented annual variability in the life history parameters of the population biology of three related penguin species: the Adelie, the gentoo and the chinstrap (Pygoscelis adeliae, P. papua and P. antarctica, respectively). This long-term study has collected twenty-five years of data on the three related species, including survival and recruitment, population size and breeding success, and diets and foraging ecology. The current project will extend the research linking penguin demography and foraging ecology to variability in the Antarctic marine ecosystem. A major focus of this work will be on the Adelie and gentoo penguin population biology data and the distribution and trophic interactions among the three Pygoscelis species during the breeding season and the non-breeding, winter period. Recent results have provided the first detailed data on the wintering distributions of Adelie and chinstrap penguins in the Antarctic Peninsula region, through the use of satellite tags and time-depth recorders to examine the post-fledging foraging. Specific topics of research include an examination of the size and sex composition of krill captured by penguins feeding chicks and krill collected concurrently by net hauls in the adjacent marine environment and the length-frequency distribution of krill collected from penguin diet samples. The over winter survival of penguin breeding adults and the recruitment of young (two to four year old) pre-breeding penguins to their natal colony will be compared to the extent of sea ice in the winter prior to the breeding season. These variables are expected to be positively correlated for the Adelie but negatively correlated to the chinstrap penguin. Detailed studies of the adult gentoo penguins, which do not disperse widely from the natal colony, will be conducted using satellite tags. The data collected in this study will improve an understanding of the structure and function of the Antarctic through research on the impact of environmental variation on the structure of upper trophic level predators such as the Pygoscelis penguins.