Renato Borras-Chavez ^1,2* Rodrigo L. Soteres ^3,4* Gabriela Gómez ⁵ Francisco Martínez ⁶ Nicolás Fernández-Ferrada ⁷ Matías Castillo-Aguilar ⁸ Fredy Moreno Azua ⁹ Catherine Dougnac ¹⁰ Cristóbal Arredondo ¹⁰ Nicholi Brown ¹ Emily S. Sperou ¹ Carolina A. Bonin ¹¹ Michael E. Goebel ¹² Alicia I. Guerrero ⁷ Marcelo Donke ⁵ Sarah S. Kienle ¹

• ¹ Department of Biology, College of Arts and Science, Baylor University, Waco, United States
• ² Center for Applied Ecology and Sustainability, Faculty of Biological Sciences, Pontifical Catholic University of Chile, Santiago, Santiago Metropolitan Region (RM), Chile
• ³ Centro de Investigación GAIA Antártica. Universidad de Magallanes, Punta Arenas, Chile
• ⁴ Other, Puerto Williams, Chile
• ⁵ Corporación Nacional Forestal (CONAF), Santiago, Santiago Metropolitan Region (RM), Chile
• ⁶ Patagonia on the trail, Puerto Natales, Chile
• ⁷ Instituto de Biología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
• ⁸ Other, Punta Arenas, Chile
• ⁹ Independent researcher, Punta Arenas, Chile
• ¹⁰ Wildlife Conservation Society (Chile), Punta Arenas, Chile
• ¹¹ Department of Biological Science, School of Science, Hampton University, Hampton, Virginia, United States
• ¹² Institute of Marine Sciences, Division of Physical & Biological Sciences, University of California, Santa Cruz, Santa Cruz, California, United States

Leopard seals have traditionally been considered Antarctic predators with a Southern Ocean distribution. Historically, sightings north of the Antarctic Polar Front were considered extralimital. However, recent studies suggest a significant presence of leopard seals in subantarctic regions. Here, we assess the spatial occurrence, residency status, and temporal trends of leopard seals in Chile using historical records, stranding reports, standardized monitoring data, photo-identification (photo ID) catalogs, and sightings from four research expeditions. We also characterize glaciers where sightings are concentrated, identifying glaciological and geomorphic attributes that prolong iceberg residency time, which is linked to high leopard seal concentrations. Based on these attributes, we evaluated other potential suitable glacial habitats in Patagonia. We obtained 438 sighting records of leopard seals from 1927 to 2023. Over the last 15 years, we documented a 4-18% annual increase in stranding events reported to national authorities. Most sightings (75%) were concentrated in two hotspots: National Park San Rafael Lagoon and Parry Fjord in Tierra del Fuego. Using photo ID catalogs, we identified 19 resident leopard seals, including 16 multi-year residents observed between 2010-2023 (10 in San Rafael, 6 in Tierra del Fuego) and 3 potential residents (observed multiple months in the same year in Tierra del Fuego). San Rafael monitoring data showed no inter-annual trend, but seasonal trends were observed. We also provide evidence of breeding in Chile, with records of at least 14 pups born and at least two females giving birth in multiple years. Our habitat characterization suggests that calving flux, fjord sinuosity, and fjord width variation are crucial for prolonging iceberg residency in hotspot areas. Based on these attributes, we identified 13 additional fjords in Patagonia as “very likely” suitable for leopard seals. Our study confirms that Patagonia is part of the species’ breeding distribution, shifting the paradigm that leopard seals are merely visitors north of the Antarctic Polar Front. Given the limited number of suitable glaciers in Chile and the potential impacts of climate change, our assessment highlights glacial retreat as a major threat to the ecosystem of this pagophilic marine apex predator in South America.