Large-scale occupancy surveys in East Antarctica discover new Adelie penguin breeding sites and reveal an expanding breeding distribution

Knowledge of spatial distribution is fundamental to ecological studies and crucial for conservation and management of species and biodiversity, but detailed, large-scale spatial data are lacking for most taxa. Although the Adelie penguin is one of the most intensively studied Antarctic vertebrates, spatial data that could aid in ecological study and conservation management are incomplete. We undertook a large-scale survey of the current breeding distribution of Adelie penguins along 3800 km of the East Antarctic coastline. The survey increased the number of known breeding locations by 50% and revealed that the breeding distribution has expanded in some parts of the survey region over the past two to three decades. The expanding breeding distribution may reflect underlying population dynamics of sustained growth and resultant density dependent effect on dispersal and movement from established breeding sites to new sites. The comprehensive, large-scale distribution data from this study will form a baseline for assessing any future changes in Adelie penguin breeding distribution, provide data for developing spatial models for predicting future changes in breeding distribution under plausible scenarios of environmental change, and contribute to the development of metapopulation models by providing estimates of local colonization and extinction probabilities under specific conditions of metapopulation change.