Constraint in the midst of growth: decadal-scale Adélie penguin (Pygoscelis adeliae) population change at Scullin and Murray Monoliths diverges from widespread increases across East Antarctica

Abstract

Understanding spatio-temporal variation in the abundance of species’ populations is an issue of central importance in ecology. Recent studies of decadal-scale change in Adelie penguin (Pygoscelisadeliae) populations around the Antarctic continent have led to insights into our understanding of the species’ population dynamics and to exploration of the ecosystem processes driving them. However, gaps in knowledge of population change still exist for many populations, especially at breeding sites distant from research stations. In this study, we estimate population change for the large Adelie penguin populations at the seldom visited and data-poor Scullin and Murray Monoliths in East Antarctica by critically assessing historical population data and extending the historical time series of population data to the present day with a recent survey. Unlike Adelie penguin populations studied elsewhere in East Antarctica, we find the Monolith populations have remained stable or decreased slightly over the past 3–4 decades. The results indicate that spatially divergent processes are driving Adelie penguin population dynamics, and that these factors may not be sufficiently represented in current explanatory or predictive population models for this species. The methods employed here provide a viable means of undertaking regular population monitoring of highly visible seabird species such as the Adelie penguin in remote and ecologically important areas such as Scullin and Murray Monoliths in the future.