Volume 54, Issue 1 p. 3-18
Original Article

A tale of two polar bear populations: ice habitat, harvest, and body condition

Karyn D. Rode

Corresponding Author

Karyn D. Rode

US Fish and Wildlife Service, Marine Mammals Management, 1011 E Tudor Road, 99503 Anchorage, AK, USA

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Elizabeth Peacock

Elizabeth Peacock

Department of Environment, Government of Nunavut, X0A 0L0 Igloolik, NU, Canada

US Geological Survey, Alaska Science Center, 4210 University Drive, 99508 Anchorage, AK, USA

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Mitchell Taylor

Mitchell Taylor

Faculty of Science and Environmental Studies, Lakehead University, 955 Oliver Road, P7B 5E1 Thunder Bay, ON, Canada

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Ian Stirling

Ian Stirling

Wildlife Research Division, Environment Canada, 5320 122 St., T6G 3S5 Edmonton, AB, Canada

Department of Biological Sciences, University of Alberta, T6G 2E9 Edmonton, AB, Canada

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Erik W. Born

Erik W. Born

Greenland Institute of Natural Resources, P.O. Box 570, 3900 Nuuk, Greenland

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Kristin L. Laidre

Kristin L. Laidre

Polar Science Center, Applied Physics Lab, University of Washington, 1013 NE, 40th Street, 98105 Seattle, WA, USA

Greenland Institute of Natural Resources, P.O. Box 570, 3900 Nuuk, Greenland

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Øystein Wiig

Øystein Wiig

National Centre for Biosystematics, Natural History Museum, University of Oslo, PO Box 1172, 0318 Oslo, Blindern, Norway

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First published: 30 November 2011
Citations: 56

An erratum to this article can be found at http://doi.org/10.1007/s10144-012-0304-y.

Abstract

One of the primary mechanisms by which sea ice loss is expected to affect polar bears is via reduced body condition and growth resulting from reduced access to prey. To date, negative effects of sea ice loss have been documented for two of 19 recognized populations. Effects of sea ice loss on other polar bear populations that differ in harvest rate, population density, and/or feeding ecology have been assumed, but empirical support, especially quantitative data on population size, demography, and/or body condition spanning two or more decades, have been lacking. We examined trends in body condition metrics of captured bears and relationships with summertime ice concentration between 1977 and 2010 for the Baffin Bay (BB) and Davis Strait (DS) polar bear populations. Polar bears in these regions occupy areas with annual sea ice that has decreased markedly starting in the 1990s. Despite differences in harvest rate, population density, sea ice concentration, and prey base, polar bears in both populations exhibited positive relationships between body condition and summertime sea ice cover during the recent period of sea ice decline. Furthermore, females and cubs exhibited relationships with sea ice that were not apparent during the earlier period (1977–1990s) when sea ice loss did not occur. We suggest that declining body condition in BB may be a result of recent declines in sea ice habitat. In DS, high population density and/or sea ice loss, may be responsible for the declines in body condition.