Long-term, landscape- and wind-driven snow conditions influence Adélie penguin colony extinctions

Abstract Context The interaction between topography and wind influences snow cover patterns, which can determine the distribution of species reliant on snow-free habitats. Past studies suggest snow accumulation creates suboptimal breeding habitats for Adélie penguins, leading to colony extinctions. However, evidence linking snow cover to landscape features is lacking. Objectives We aimed to model landscape-driven snow cover patterns, identify long-term weather changes, and determine the impact of geomorphology and snow conditions on penguin colony persistence. Methods We combined remotely sensed imagery, digital surface models, and > 30 years of weather data with penguin population monitoring from 1975 to 2022 near Palmer Station, west Antarctic Peninsula. Using a multi-model approach, we identified landscape factors driving snow distribution on two islands. Historic and current penguin sub-colony perimeters were used to understand habitat selection, optimal habitat features, and factors associated with extinctions. Results Decadal and long-term trends in wind and snow conditions were detected. Snow accumulated on lower elevations and south-facing slopes driven by the north-northeasterly winds while Adélie penguins occupied higher elevations and more north-facing slopes. On Torgersen Island, sub-colonies on south aspects have gone extinct, and only five of the 23 historic sub-colonies remain active, containing 7% of the 1975 population. Adélie penguins will likely be extinct on this island in < 25 years. Conclusions Adélie penguin populations are in decline throughout the west Antarctic Peninsula with multiple climate and human impacts likely driving Adélie penguins towards extinction in this region. We demonstrate precipitation has detrimental effects on penguins, an often overlooked yet crucial factor for bird studies.