Tracking the foraging migrations of Marion Island southern elephant seals (Mirounga leonina) during their first year of life

Abstract

The first year of life is critical for large mammals to acquire foraging and predator avoidance skills. Southern elephant seal (Mirounga leonina) pups wean at approximately three weeks of age and depart on their first foraging trips in midsummer, typically remaining at sea for three to four months before returning to their natal islands. We describe the foraging trips (n = 29) of 16 underyearling southern elephant seals from sub-Antarctic Marion Island and compare these with trips (n = 152) of 94 older seals from the same population. While subadults (prebreeding age) and adult females (breeding age) displayed directional travel, underyearlings traveled in multiple directions from the island with no evidence of repeatability of travel directions within or between individuals and years. Maiden trips took longer to complete than subsequent trips during the first year of life, but we found no evidence for significant changes in other track metrics between the first three foraging trips. The comparatively inconsistent movement patterns of underyearlings suggest that foraging strategies of individuals are influenced by their learning and/or success during the first year of life and that individual level consistency in successful foraging strategies only become apparent in subsequent years.