Abstract
ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 36:1-14 (2018) - DOI: https://doi.org/10.3354/esr00886 Theme Section: Biologging in conservation Changes in winter and spring resource selection by polar bears Ursus maritimus in Baffin Bay over two decades of sea-ice loss Kristin L. Laidre1,2,*, Harry Stern1, Erik W. Born2, Patrick Heagerty3, Stephen Atkinson4, Øystein Wiig5, Nicholas J. Lunn6, Eric V. Regehr1, Richard McGovern1, Markus Dyck4 1Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA 98105, USA 2Greenland Institute of Natural Resources, PO Box 570, Nuuk 3900, Greenland 3Department of Biostatistics, University of Washington, Seattle, WA 98195, USA 4Wildlife Research Section, Department of Environment, Government of Nunavut, PO Box 209, Igloolik, Nunavut X0A 0L0, Canada 5Natural History Museum, University of Oslo, PO Box 1172, Blindern, 0318 Oslo, Norway 6Environment and Climate Change Canada, CW-422 Biological Sciences Building, University of Alberta, Edmonton, AB T6G 2E9, Canada *Corresponding author: klaidre@uw.edu ABSTRACT: Loss of Arctic sea ice has implications for the distribution and population structure of ice-dependent species such as polar bears Ursus maritimus. We used remotely sensed sea-ice concentration data for Baffin Bay, Canada, and satellite telemetry for adult female polar bears in the 1990s (n = 43) and 2000s (n = 38) to assess whether sea-ice habitat changes have influenced movements and habitat selection. Both the timing and availability of sea-ice habitat changed significantly between the 1990s and 2000s. Mean sea-ice concentration in June-October declined from 22 to 12%. Spring sea-ice retreat occurred 2 wk earlier and fall sea-ice advance 2 wk later in the 2000s. These changes translated directly to changes in habitat use by polar bears. In the 2000s, bears used significantly lower sea-ice concentrations in winter and spring. Also, bears were significantly closer to land in all months, except at the end of spring breakup when they remained on offshore sea ice as long as possible, likely to maximize foraging time prior to coming on land where they are largely food deprived. The presence of summer offshore sea ice facilitated broad movement of bears in the 1990s; however, this ice disappeared in the 2000s and resulted in significant declines in monthly movement rates. In the 2000s, adult females selected for lower sea-ice concentrations if they facilitated access to the continental shelf (<300 m). Our findings indicate that significant changes in available sea-ice habitat and habitat use in Baffin Bay have occurred since the mid-1990s and this subpopulation will likely experience negative population-level impacts related to a changing climate in the coming decades. In some other parts of the Arctic, such changes have preceded negative nutritional and demographic impacts. KEY WORDS: Arctic · Canada · Greenland · Habitat models · Polar bear · Ursus maritimus · Sea ice Full text in pdf format NextCite this article as: Laidre KL, Stern H, Born EW, Heagerty P and others (2018) Changes in winter and spring resource selection by polar bears Ursus maritimus in Baffin Bay over two decades of sea-ice loss. Endang Species Res 36:1-14. https://doi.org/10.3354/esr00886 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 36. Online publication date: May 08, 2018 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2018 Inter-Research.
Highlights
Polar bears are distributed throughout the circumpolar Arctic in 19 subpopulations (PBSG 2010)
During late spring and summer break-up, sea ice recedes from Greenland across Baffin Bay; the last remnants of ice typically occur off the coast of Baffin Island
Our sensitivity modeling using the subset of 1990s adult females (AFs) bears collared in spring on the sea ice in West Greenland (n = 9) compared with the full sample of 2000s bears showed the same habitat selection in spring. These analyses demonstrate that bears captured in West Greenland in spring used the same geographical areas, had the same seasonal movement patterns, and the same habitat preferences as bears captured on the east coast of Baffin Island in fall
Summary
Polar bears are distributed throughout the circumpolar Arctic in 19 subpopulations (PBSG 2010). Additional studies have documented use of less optimal sea-ice habitat in several polar bear subpopulations but have not found evidence for negative demographic effects (e.g. Durner et al 2009, Wilson et al 2014, Laidre et al 2015a, McCall et al 2016, Lone et al 2018). This indicates that a time lag exists between habitat loss and detection of population-level impacts, and suggests that changes in habitat use may be a useful indicator of future demographic change. Resource managers need improved knowledge and tools to effectively manage and conserve polar bears under climate-induced sea-ice loss while concurrently managing subsistence harvest (Regehr et al 2017a) and mitigating human−polar bear conflicts (Wilder et al 2017)
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