ONTOGENY OF MOVEMENTS AND FORAGING RANGES IN THE AUSTRALIAN SEA LION

摘要

This study tracked the movements of Australian sea lion (Neophoca cmerea) pups, juveniles, and adult females to identify home ranges and determine if young sea lions accompanied their mothers at sea. Satellite tags were deployed on nine 15-mo-old pups, nine 23-mo-old juveniles, and twenty-nine adult female Australian sea lions at Seal Bay Conservation Park, Kangaroo Island, South Australia. Females did not travel with their offspring at sea, suggesting young Australian sea lions learn foraging behaviors independently. Although home ranges increased with age, 23-mo-old juveniles had not developed adult movement capacity and their range was only 40.6% of the adult range. Juveniles traveled shorter distances (34.8 +-5.5 km) at slower speeds (2.0 +- 0.3km/h) than adults (67.9 +- 3.5 km and 3-9 +-0.3 km/h). Young sea lions also stayed in shallower waters; sea floor depths of mean locations were 48 +- 7 m for juveniles and 74 +- 2 m for females. Restricted to shallow coastal waters, pups and juveniles are more likely to be disproportionately impacted by human activities. With limited available foraging habitat, young Australian sea lions appear particularly vulnerable to environmental alterations resulting from fisheries or climate change.