Demographic characteristics of the Adélie penguin population on Béchervaise Island after 12 years of study
Demographic parameters (age-specific survival rates, fecundity levels and population numbers) were analysed for the Béchervaise Island Adélie penguin colony in eastern Antarctica after 12 years of monitoring under the CCAMLR Ecosystem Monitoring Program (CEMP). A life table was constructed, and predicted rates of population growth and breeding success calculated. The population model predicted an annual population growth rate of 0.3% compared to the 1.2–1.8% increase per annum indicated from field counts. Underestimation of adult survival rates was considered the most likely explanation for the discrepancy. As is the case for most long-lived seabird species, growth/decline rates of the Adélie penguin population at Béchervaise Island were found to be more sensitive to changes in annual survival rates, especially of young breeding adults, than to changes in fecundity parameters. Results are discussed in comparison with data from a declining Adélie penguin population in the Ross Sea studied during the 1960s and 1970s (Ainley et al., 1983), and in relation to other CEMP parameters, environmental factors and fishery regulations. The data collection and analysis methods outlined in this paper provide a basis for the development of data reporting formats for CEMP Standard Method A4.