Do penguins care about on-paper boundaries? Conservation implications of spatio-temporal winter consistency in an Antarctic sentinel species

Understanding the spatial and temporal at-sea distribution of marine predators throughout their annual cycle is crucial for identifying priority areas for conservation in the Southern Ocean. However, the delimitation of boundaries of the proposed East Antarctic Marine Protected Area (EAMPA) is largely based on species' breeding distributions, overlooking seasonal and annual shifts driven by sea ice variability. We studied the non-breeding distribution and space use of a key Antarctic eco-indicator species, the Adélie penguin, by tracking 62 individuals from Terre Adélie over five years using geolocators. Moulting occurred in areas of low sea ice concentration (SIC), whereas during winter, penguins migrated on average 1550 km westward from the colony to areas along the sea ice edge with high SIC (75 %). The inter-annual overlap of wintering grounds revealed high spatio-temporal consistency, indicating productive regions. Despite variability across years, tracked individuals moulted predominantly outside the proposed EAMPA, and only 16.3 % of winter locations fell within its boundaries. These findings provide new insights into the non-breeding ecology of Adélie penguins, and highlight a relevant gap in spatial coverage of critical moulting and wintering areas of this highly mobile species in the current EAMPA proposal. • Tracked Adélie penguins moulted in areas of low sea ice concentration. • The penguins migrated westward to areas of high sea ice concentration. • The penguins showed high consistency in the use of wintering grounds across years. • The penguins spent limited time within the proposed MPA during moult and winter. • Species' non-breeding distribution is not integrated in East Antarctic MPA design.