Breeding emperor penguins show interannual recurrence in shelf-break associated foraging areas across contrasting sea ice conditions in the northwestern Weddell Sea

Abstract The emperor penguin Aptenodytes forsteri is highly sea ice dependent and vulnerable to climate change, yet the at-sea distribution and habitat associations of breeding adults remain poorly understood for colonies in the western Weddell Sea. We tracked nine breeding adults from Snow Hill Island, the northernmost known colony, during chick-rearing in 2023-24 and 2025-26, and analysed 38 foraging trips using kernel utilisation distributions, habitat-selection models and hidden Markov models. Penguins repeatedly used a region east and northeast of the colony aligned with shelf-break-associated waters, with a smaller westward component towards waters close to glaciated coastal margins along the Antarctic Peninsula. Space use was broader and trips were longer in 2025-26, when core-use areas occurred under much higher sea ice concentration, yet overlap metrics indicated broad fidelity to the same geographical foraging region. Habitat use was associated with distance to the colony, mean sea ice concentration, with responses differing between study years, and the combined influence of shelf-break position and distance to glaciated coastal margins. Behavioural states varied with diel cycle and sea ice concentration, with foraging and resting associated with higher sea ice concentration than transit. The proposed Weddell Sea Marine Protected Area encompassed 57.9–75.1% of study-year foraging distributions, while smaller overlap occurred with the proposed Western Antarctic Peninsula and South Scotia Arc Marine Protected Area, highlighting the relevance of these areas for spatial conservation planning.