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Polar Biology

, Volume 29, Issue 12, pp 1052–1062 | Cite as

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

  • Jaume ForcadaEmail author
  • Sarah L. Robinson
Original Paper

Abstract

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 \((\bar{x} = 12; 95\%\hbox{CI}: 5\hbox{--}28).\) 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.

Keywords

Residency Time Leopard Seal Macaroni Penguin Capture Occasion Seasonal Resident 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgments

We are grateful to H.F. Taylor and A. Thomas who helped in the collection of photo-identification data at Bird Island, South Georgia. P. Bucktrout from the British Antarctic Survey (BAS) Photo Unit provided invaluable support in the creation of the leopard seal catalogue and database. I.P. Forster improved the manuscript with helpful comments. This work was carried out in support of the BAS DISCOVERY 2010 and LTMS Core Science Programmes at South Georgia.

References

  1. Ainley DG, Ballard G, Karl BJ, Dugger KM (2005) Leopard seal predation rates at penguin colonies of different size. Antarct Sci 17:335–340CrossRefGoogle Scholar
  2. Barlow KE, Boyd IL, Croxall JP, Reid K, Staniland IJ, Brierley AS (2002) Are penguins and seals in competition for Antarctic krill at South Georgia? Mar Biol 140:205–213CrossRefGoogle Scholar
  3. Bester MN, Roux J-P (1986) Summer presence of leopard seals Hydrurga leptonyx at the Courbet Peninsula, Iles Kerguelen. S Afr J Antarct Res 16:29–32Google Scholar
  4. Bester MN, Ferguson JWH, Jonker FC (2002) Population densities of pack-ice seals in the Lazarev Sea, Antarctica. Antarct Sci 14:123–127CrossRefGoogle Scholar
  5. Bonner WN (1958) Notes on the southern fur seal in South Georgia. Proc Zool Soc London 130:241–252Google Scholar
  6. Borsa P (1990) Seasonal occurrence of the leopard seal, (Hydrurga leptonyx) in the Kerguelen Islands. Can J Zool 68:405–408Google Scholar
  7. Boveng PL, Hiruki LM, Schwartz MK, Bengtson JL (1998) Population growth of Antarctic fur seals: limitation by a top predator, the leopard seal? Ecology 79:2863–2877CrossRefGoogle Scholar
  8. Boyd IL (1993) Pup production and distribution of breeding Antarctic fur seals Arctocephalus gazella at South Georgia. Antarct Sci 5:17–24Google Scholar
  9. Burnham KP, Anderson DR (2002) Model selection and multi-model inference. A practical information-theoretic approach, 2nd edn. Springer, Berlin Heidelberg New YorkGoogle Scholar
  10. Catchpole EA, Morgan BJT (1997) Detecting parameter redundancy. Biometrika 84:187–196CrossRefGoogle Scholar
  11. Choquet R, Pradel R (2003) User’s manual for SODA. Mimeographed document, CEFE/CNRS, Montpellier (http://ftp.cefe.cnrs-mop.fr/biom/Soft-CR/)
  12. Choquet R, Reboulet A-M, Lebreton J-D, Gimenez O, Pradel R (2005) U-CARE 2.2 User’s Manual. CEFE, Montpellier (http://ftp.cefe.cnrs.fr/biom/Soft-CR/)
  13. Erickson AW, Bester MN, Laws RM (1993) Marking techniques. In: Laws RM (ed) Antarctic seals. Cambridge University Press, Cambridge, pp 89–118Google Scholar
  14. Forcada J, Aguilar A (2000) Use of photographic identification in capture–recapture studies of Mediterranean monk seals. Mar Mamm Sci 16:767–793CrossRefGoogle Scholar
  15. Forcada J, Hammond PS, Aguilar A (1999) The status of the Mediterranean monk seal in the western Sahara and the implications of a mass mortality. Mar Ecol Prog Ser 188:249–261Google Scholar
  16. Forcada J, Trathan PN, Reid K, Murphy EJ (2005) The effects of global climate variability in pup production of Antarctic fur seals. Ecology 86:2408–2417Google Scholar
  17. Forcada J, Trathan PN, Reid K, Murphy EJ, Croxall JP (2006) Contrasting population changes in sympatric penguin species in association with climate warming. Glob Change Biol 12:411–423CrossRefGoogle Scholar
  18. Fraser WR, Hofmann EE (2003) A predator’s perspective on causal links between climate change, physical forcing and ecosystem response. Mar Ecol Prog Ser 265:1–15Google Scholar
  19. Gilbert JR, Erickson AW (1977) Distribution and abundance of seals in the pack ice of the Pacific sector of the Southern Ocean. In: Llano GA (ed) Adaptations within Antarctic ecosystems. Proceedings of the third Scientific Committee on Antarctic Research symposium on Antarctic Biology. Smithsonian Institution, Washington, pp 703–740Google Scholar
  20. Hammond PS (1990) Heterogeneity in the Gulf of Maine? Estimating humpback whale population size when capture probabilities are not equal. Rep Int Whaling Comm (special issue) 12:135–139Google Scholar
  21. Hammond PS, Sears R, Bérubé M (1990) A note on problems in estimating the number of blue whales in the Gulf of St. Lawrence from photo-identification data. Rep Int Whaling Comm (special issue) 12:141–142Google Scholar
  22. Hiby L, Lovell P (1990) Computer aided matching of natural markings: a prototype system for grey seals. Rep Int Whaling Comm (special Issue) 12:57–61Google Scholar
  23. Hiby L, Lovell P (1997) Abundance estimates of grey seals in summer based on photo-identification data. Final report to MAFF under contract number MF0707. Available at: Conservation Research Ltd, 110 Hinton Way, Gt. Shelford, Cambridge, CB2 5AL, UKGoogle Scholar
  24. Hiruki LM, Schwartz MK, Boveng PL (1999) Hunting and social behaviour of leopard seals (Hydrurga leptonyx) at Seal Island, South Shetland Islands, Antarctica. J Zool Lond 249:97–109Google Scholar
  25. Jessopp MN, Forcada J, Reid K, Trathan PN, Murphy EJ (2004) Winter dispersal of leopard seals (Hydrurga leptonyx): environmental factors influencing demographics and seasonal abundance. J Zool Lond 263:251–258Google Scholar
  26. Laws RM (1957) On the growth rates of the leopard seal, Hydrurga leptonyx (De Blainville, 1820). Saugetierkundliche Mitteilungen 5:49–55Google Scholar
  27. Link WA, Barker RJ (2005) Modeling association among demographic parameters in analysis of open population capture–recapture data. Biometrics 61:46–54PubMedCrossRefGoogle Scholar
  28. McConkey SD (1999) Photographic identification of the New Zealand sea lion: a new technique. N Z J Mar Freshw Res 33:63–66CrossRefGoogle Scholar
  29. Pradel R (1996) Utilization of capture-mark-recapture for the study of recruitment and population growth rate. Biometrics 52:703–709CrossRefGoogle Scholar
  30. Pradel R, Hines JE, Lebreton J-D, Nichols JD (1997) Estimating survival rate and proportion of transients using capture–recapture data from open populations. Biometrics 53:88–99CrossRefGoogle Scholar
  31. Rakusa-Suszczewski S, Sierakowski K (1993) Pinnipeds in Admiralty Bay, King George Island, South Shetlands (1988–1992). Pol Polar Res 14:441–454Google Scholar
  32. Rogers TL, Hogg CJ, Irvine A (2005) Spatial movement of adult leopard seals (Hydrurga leptonyx) in Prydz Bay, Eastern Antarctica. Polar Biol 28:456–463CrossRefGoogle Scholar
  33. Rounsevell D, Eberhard I (1980) Leopard seals, Hydrurga leptonyx (Pinnipedia), at Macquarie Island from 1949 to 1979. Aust Wildl Res 7:403–415CrossRefGoogle Scholar
  34. Rounsevell D, Pemberton D (1994) The status and seasonal occurrence of leopard seals, Hydrurga leptonyx, in Tasmanian waters. Aust Mamm 17:97–102Google Scholar
  35. Schwarz CJ, Arnason AN (1996) A general methodology for the analysis of capture-recapture experiments in open populations. Biometrics 52:860–873CrossRefGoogle Scholar
  36. Schwarz CJ, Bailey RE, Irvine JE, Dalziel FC (1993) Estimating salmon spawning escapement using capture-recapture methods. Can J Fish Aquat Sci 50:1181–1191CrossRefGoogle Scholar
  37. Shaub M, Pradel R, Jenni L, Lebreton J-D (2001) Migrating birds stop over longer than usually thought: an improved capture–recapture analysis. Ecology 82:852–859CrossRefGoogle Scholar
  38. Siniff DB (1991) An overview of the ecology of Antarctic seals. Am Zool 31:113–149Google Scholar
  39. Siniff DB, Stone S (1985) The role of the leopard seal in tropho-dynamics of the Antarctic marine ecosystem. In: Siegfried WR, Condy PR, Laws RM (eds) Antarctic nutrient cycles and food webs. Springer, Berlin Heidelberg New York, pp 555–560Google Scholar
  40. Testa JW, Oehlert G, Ainley DG, Bengtson JL, Siniff DB, Laws RM, Rounsevell D (1991) Temporal variability in Antarctic marine ecosystems: periodic fluctuations in the phocid seals. Can J Fish Aquat Sci 48:631–639CrossRefGoogle Scholar
  41. Trathan PN, Murphy EJ, Forcada J, Croxall JP, Reid K, Thorpe SE (2006) Physical forcing in the southwest Atlantic: ecosystem control. In: Boyd IL, Wanless S, Camphuysen CJ (eds) Top predators in marine ecosystems. Cambridge University Press, Cambridge, pp 28–45Google Scholar
  42. Walker TR, Boyd IL, McCafferty DJ, Huin N, Taylor RI, Reid K (1998) Seasonal occurrence and diet of leopard seals (Hydrurga leptonyx) at Bird Island, South Georgia. Antarct Sci 10:75–81Google Scholar
  43. White GC, Burnham KP (1999) Program MARK: survival estimation from populations of marked animals. Bird Study 46(Suppl):120–138CrossRefGoogle Scholar
  44. Yochem PK, Stewart BS, Mina M, Zorin A, Sadovov V, Yablokov A (1990) Non-metrical analyses of pelage patterns in demographic studies of harbor seals. Rep Int Whaling Comm (special issue) 12:87–90Google Scholar

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  1. 1.British Antarctic Survey, Natural Environment Research CouncilCambridgeUK

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