Population abundance, structure and turnover estimates for leopard seals during winter dispersal combining tagging and photo-identification data

• Published in: Polar Biology
• Main Authors: Forcada, Jaume, Robinson, Sarah L.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Springer 2006
• Subjects: Zoology; Bird Island; Leopard Seal; Leopard Seals; Polar Biology
• Online Access: http://nora.nerc.ac.uk/id/eprint/936/; https://doi.org/10.1007/s00300-006-0149-y

Winter dispersal in leopard seals is poorly understood because of its low density in most of its range. By combining photo-identification and tagging data from Bird Island, South Georgia, in mark-recapture models, leopard seal abundance over the winter of 2005 was estimated as 118 (95% CI: 78–179). Seasonal residents arrived earlier and stayed longer around the island (27 days; 95% CI: 23–32) and their numbers were low and stable over the winter Most of the seals (81; 95% CI: 31–130) were young transients, stayed only 1–7 days, and arrived later in the season. This suggests (1) very low predatory pressure upon the locally abundant prey populations; (2) two different patterns of winter movements: a winter migration in adult seals with long-term site fidelity, and large numbers of juveniles in dispersal possibly attracted by locally abundant prey colonies, and potentially influenced by increased environmental stress.