Site fidelity and behaviour of killer whales ( Orcinus orca) at Sea Lion Island in the Southwest Atlantic

Abstract

Using shore-based observations and photographic identification of killer whales (Orcinus orca) at Sea Lion Island (52°26'S, 59°05'W) in the Falklands/Malvinas archipelago, we identified a small group (6 to 12 animals) targeting a southern elephant seal (Mirounga leonina) breeding colony. Sightings during 2004-05 and photographic matches from the early 1990s suggest site fidelity. Behavioural observations revealed ambush and shallow water hunting techniques along rocky outcrops and two beaches used by elephant seal pups and juveniles. A single successful attack and three unsuccessful attempts were recorded. RESUMEN: Observaciones y foto-identificación de orcas (Orcinus orca) en la Isla Sea Lion (52°26'S, 59°05'W) en el archipiélago de las Islas Malvinas/Falkland Islands, identificó a un pequeño grupo (6 a 12 animales) asechando y cazando una colonia reproductiva de elefantes marinos (Mirounga leonina). Avistamientos durante 2004-05 y comparaciones fotográficas de los 1990's revelan la fidelidad del sitio. Observaciones de su comportamiento revelaron técnicas de emboscada y caza en aguas costeras poco profundas, utilisadas por cachorros y juveniles. Fueron registrados cuatro ataques, de los cuales solo uno tuvo éxito.