Abstract
<title>Abstract</title> <p> The emperor penguin <italic>Aptenodytes forsteri</italic> 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/slope waters, with a smaller westward component towards glacial waters 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, season-specific sea-ice concentration, and the combined influence of shelf/slope position and glacier-front proximity, with evidence of individual variation in habitat use. 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 53.6–75.3% of seasonal foraging distributions, highlighting its relevance for spatial conservation planning. </p>