Abstract The collaborative project investigates the demographic mechanisms responsible for dramatic growth in existing Adelie Penguins Pygoscelis adeliae colonies, and the founding of new ones, in the Ross Sea. Research will also investigate the possibility that growth is related to documented climate change in the region by: 1) distinguishing the relative importance of the key resources that constrain growth of colonies--availability of nesting habitat vs. access to food -- and 2) examining behavioral mechanisms (philopatry -- the immigration/emigration balance, and/or breeding effort/success) that influence colony growth as a function of initial size and distribution. This will be the first empirical a piori study to consider the geographic structuring of a seabird population. Results will increase understanding of 1) population regulation and patterns of dispersion, and 2) effects of climate change, mediated through changes in sea-ice cover, on penguin populations. In addition, results will provide a context in which to interpret conflicting data on penguin population trends from existing programs that use Adelie penguins as an indicator species for point source anthropogenic impacts on Antarctic resources (e.g., fishery catches, disturbance by tourism). The 7 years of research (4 full and 1 partial years funded by NSF) includes intensive field study conducted at three Ross Island penguin colonies. The study will quantify reproductive effort and success, food availability (access to food), diet quality, habitat use and immigration/emigration relative to colony size and environmental conditions (i.e., pack-ice cover). Methods will bring together several well-established techniques that have been successfully but infrequently used in Antarctic biological research: aerial photography to evaluate availability of nesting habitat, microwave images of sea-ice concentration to assess availability of feeding habitat, analysis of stable isotopes to evaluate food quality, radio telemetry to assess overlap in colony feeding areas, and automatic systems to log aspects of reproductive effort. The research builds on, and collaborates with the efforts of Landcare Research New Zealand (LCRNZ), which will have conducted two preliminary field seasons, including testing of new equipment, will continue through the period of effort, and which is independently funded. Researchers from the University of California Santa Cruz, University of Wisconsin, and Avid Inc will collaborate with those from H.T. Harvey & Associates and LCRNZ to accomplish project goals.
