Polar Biology

, Volume 40, Issue 4, pp 753–763 | Cite as

Summer refugia of polar bears (Ursus maritimus) in the southern Beaufort Sea

Original Paper


Climate change is altering habitats and causing changes to species behaviors and distributions. Rapid changes in Arctic sea ice ecosystems have increased the need to identify critical habitats for conservation and management of species such as polar bears (Ursus maritimus). We examined the distribution of adult female and subadult male and female polar bears tracked by satellite telemetry (n = 64 collars) in the southern Beaufort Sea, Canada, to identify summer refugia in 2007–2010. Using utilization distributions, we identified terrestrial and sea ice areas used as summer refugia when nearshore sea ice melted. Habitat use areas varied between months, but interannual variation was not significant. Overall, bears made high use of ice over shallow waters, and bears that remained near terrestrial areas used sea ice (presumably to hunt from) when it was available. The majority of the bears remained on sea ice during summer and used the edge of the pack ice most notably west of Banks Island, Canada. A mean of 27 % (range 22–33 %) of bears used terrestrial areas in Alaska and use was concentrated near the remains of subsistence harvested bowhead whales (Balaena mysticetus). Energetic expenditure is anticipated to increase as bears are required to travel further on a seasonal basis.


Polar bear Ursus maritimus Beaufort Sea Distribution Sea ice Kernel density 



We gratefully acknowledge support from ArcticNet, Canadian Association of Zoos and Aquariums, Canadian Circumpolar Institute’s Boreal Alberta Research, Canadian Wildlife Federation, Environment Canada, Hauser Bears, Inuvialuit Game Council, Natural Sciences and Engineering Research Council of Canada, Northwest Territories Department of Environment and Natural Resources—Inuvik Region, Polar Bears International, Polar Continental Shelf Project, Quark Expeditions Ltd., United States Department of the Interior (Bureau of Ocean Energy Management), and World Wildlife Fund (Canada and International). We furthermore thank Marie Auger-Méthé, Oliver Barker, Seth Cherry, Stephen Hamilton, Alysa McCall, Peter Molnár, Nick Pilfold, and Vicki Sahanatien for assistance in the field and pilot Mike Woodcock.


  1. Aagaard K (ed) (1984) The Beaufort Undercurrent. Academic Press, OrlandoGoogle Scholar
  2. Amstrup SC, Gardner C (1994) Polar bear maternity denning in the Beaufort Sea. J Wildl Manag 58:1–10CrossRefGoogle Scholar
  3. Amstrup SC, Durner GM, Stirling I, Lunn NN, Messier F (2000) Movements and distribution of polar bears in the Beaufort Sea. Can J Zool 78:948–966CrossRefGoogle Scholar
  4. Amstrup SC, Stirling I, Smith TS, Perham C, Thiemann GW (2006) Recent observations of intraspecific predation and cannibalism among polar bears in the southern Beaufort Sea. Polar Biol 29:997–1002CrossRefGoogle Scholar
  5. Arrigo KR, van Dijken G, Pabi S (2008) Impact of a shrinking Arctic ice cover on marine primary production. Geophys Res Lett. doi: 10.1029/2008GL035028 Google Scholar
  6. Bekoff M, Mech LD (1984) Simulation analyses of space use—home range estimates, variability, and sample-size. Behav Res Methods Instrum Comput 16:32–37. doi: 10.3758/bf03201046 CrossRefGoogle Scholar
  7. Bentzen TW, Follmann EH, Amstrup SC, York GS, Wooller MJ, O’Hara TM (2007) Variation in winter diet of southern Beaufort Sea polar bears inferred from stable isotope analysis. Can J Zool 85:596–608CrossRefGoogle Scholar
  8. Block WM, Brennan LA (1993) The habitat concept in ornithology: theory and applications. In: Power DM (ed) Current ornithology, vol 11. Plenum Press, New YorkGoogle Scholar
  9. Boulanger JG, White GC (1990) A comparison of home range estimators using Monte-Carlo simulation. J Wildl Manag 54:310–315CrossRefGoogle Scholar
  10. Bromaghin JF et al (2015) Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline. Ecol Appl 25:634–651CrossRefPubMedGoogle Scholar
  11. Brown JH (1984) On the relationship between abundance and distribution of species. Am Nat 124:255–279CrossRefGoogle Scholar
  12. Carmack EC, Macdonald RW (2002) Oceanography of the Canadian shelf of the Beaufort Sea: a setting for marine life. Arctic 55:29–45CrossRefGoogle Scholar
  13. Cherry SG, Derocher AE, Stirling I, Richardson E (2009) Fasting physiology of polar bears in relation to environmental change and breeding behavior in the Beaufort Sea. Polar Biol 32:383–391CrossRefGoogle Scholar
  14. Cherry SG, Derocher AE, Hobson KA, Stirling I, Thiemann GW (2011) Quantifying dietary pathways of proteins and lipids to tissues of a marine predator. J Appl Ecol 48:373–381. doi: 10.1111/j.1365-2664.2010.01908.x CrossRefGoogle Scholar
  15. Coachman LK, Aagaard K (1974) Physical oceanography of Arctic and Subarctic Seas. In: Herman Y (ed) Marine geology and oceanography of the Arctic seas. Springer, New York, pp 1–72CrossRefGoogle Scholar
  16. Comiso JC, Parkinson CL, Gersten R, Stock L (2008) Accelerated decline in the Arctic sea ice cover. Geophys Res Lett 35:L01703. doi: 10.1029/2007gl031972 CrossRefGoogle Scholar
  17. Cooper PF (1974) Landfast ice in the southeastern part of the Beaufort Sea. In: Reed JC, Sater JE (eds) The coast and shelf of the Beaufort Sea. The Arctic Institute of North America, Arlington, pp 235–242Google Scholar
  18. Derocher AE, Garner GW, Lunn NJ, Wiig Ø (eds) (1998) Polar bears: proceedings of the twelfth working meeting of the IUCN/SSC polar bear specialist group. IUCN, Gland and CambridgeGoogle Scholar
  19. Derocher AE, Wiig Ø, Andersen M (2002) Diet composition of polar bears in Svalbard and the western Barents Sea. Polar Biol 25:448–452. doi: 10.1007/s00300-002-0364-0 Google Scholar
  20. Derocher AE, Lunn NJ, Stirling I (2004) Polar bears in a warming climate. Integr Comp Biol 44:163–176CrossRefPubMedGoogle Scholar
  21. Derocher AE, Aars J, Amstrup SC, Cutting A, Lunn NJ, Molnár PK, Obbard ME, Stirling I, Thiemann GW, Vongraven D, Wiig Ø, York G (2013) Rapid ecosystem change and polar bear conservation. Conserv Lett 6:368–375. doi: 10.1111/conl.12009 Google Scholar
  22. Duong T (2007) Ks: kernel density estimation and kernel discriminant analysis for multivariate data in r. J Stat Softw 21:1–16CrossRefGoogle Scholar
  23. Duong T, Hazelton ML (2003) Plug-in bandwidth matrices for bivariate kernel density estimation. J Nonparametr Stat 15:17–30CrossRefGoogle Scholar
  24. Durner GM et al (2009) Predicting 21st-century polar bear habitat distribution from global climate models. Ecol Monogr 79:25–58. doi: 10.1890/07-2089.1 CrossRefGoogle Scholar
  25. Durner GM, Whiteman JP, Harlow HJ, Amstrup SC, Regehr EV, Ben-David M (2011) Consequences of long-distance swimming and travel over deep-water pack ice for a female polar bear during a year of extreme sea ice retreat. Polar Biol 34:975–984. doi: 10.1007/s00300-010-0953-2 CrossRefGoogle Scholar
  26. Fieberg J (2007) Kernel density estimators of home range: smoothing and the autocorrelation red herring. Ecology 88:1059–1066CrossRefPubMedGoogle Scholar
  27. Fischbach AS, Amstrup SC, Douglas DC (2007) Landward and eastward shift of Alaskan polar bear denning associated with recent sea ice changes. Polar Biol 30:1395–1405CrossRefGoogle Scholar
  28. Frost KJ, Lowry LF, Pendleton G, Nute HR (2004) Factors affecting the observed densities of ringed seals, Phoca hispida, in the Alaskan Beaufort Sea, 1996–99. Arctic 57:115–128CrossRefGoogle Scholar
  29. Gaston AT, Gilchrist HG, Mallory ML, Smith PA (2009) Changes in seasonal events, peak food availability, and consequent breeding adjustment in a marine bird: a case of progressive mismatching. Condor 111:111–119CrossRefGoogle Scholar
  30. Gitzen RA, Millspaugh JJ, Kernohan BJ (2006) Bandwidth selection for fixed-kernel analysis of animal utilization distributions. J Wildl Manag 70:1334–1344CrossRefGoogle Scholar
  31. Gleason J, Rode K (2009) Polar bear distribution and habitat association reflect long-term changes in fall sea ice conditions in the Alaskan Beaufort Sea. Arctic 62:405–417CrossRefGoogle Scholar
  32. Hall LS, Krausman PR, Morrison ML (1997) The habitat concept and a plea for standard terminology. Wildl Soc B 25:173–182Google Scholar
  33. Hansen AS, Nielsen TG, Levinsen H, Madsen SD, Thingstad TF, Hansen BW (2003) Impact of changing ice cover on pelagic productivity and food web structure in Disko Bay, west Greenland: a dynamic model approach. Deep Sea Res I 50:171–187. doi: 10.1016/s0967-0637(02)00133-4 CrossRefGoogle Scholar
  34. Harwood LA, Smith TG, Melling H, Alikamik J, Kingsley MCS (2012) Ringed seals and sea ice in Canada’s western Arctic: harvest-based monitoring 1992–2011. Arctic 65:377–390. doi: 10.2307/41758907 Google Scholar
  35. Harwood LA, Smith TG, George JC, Sandstrom SJ, Walkusz W, Divoky GJ (2015) Change in the Beaufort Sea ecosystem: diverging trends in body condition and/or production in five marine vertebrate species. Prog Oceanogr 136:263–273. doi: 10.1016/j.pocean.2015.05.003 CrossRefGoogle Scholar
  36. Hitch AT, Leberg PL (2007) Breeding distributions of North American bird species moving north as a result of climate change. Conserv Biol 21:534–539. doi: 10.1111/j.1523-1739.2006.00609.x CrossRefPubMedGoogle Scholar
  37. Hunter CM, Caswell H, Runge MC, Regehr EV, Amstrup SC, Stirling I (2010) Climate change threatens polar bear populations: a stochastic demographic analysis. Ecology 91:2883–2897. doi: 10.1890/09-1641.1 CrossRefPubMedGoogle Scholar
  38. Jakobsson M et al (2008) An improved bathymetric portrayal of the Arctic Ocean: implications for ocean modeling and geological, geophysical and oceanographic analyses. Geophys Res Lett. doi: 10.1029/2008gl033520 Google Scholar
  39. Johannessen OM, Miles MW (2011) Critical vulnerabilities of marine and sea ice-based ecosystems in the high Arctic. Reg Environ Change 11:S239–S248. doi: 10.1007/s10113-010-0186-5 CrossRefGoogle Scholar
  40. Kelly AE, Goulden ML (2008) Rapid shifts in plant distribution with recent climate change. P Natl Acad Sci USA 105:11823–11826. doi: 10.1073/pnas.0802891105 CrossRefGoogle Scholar
  41. Keppel G et al (2012) Refugia: identifying and understanding safe havens for biodiversity under climate change. Glob Ecol Biogeogr 21:393–404. doi: 10.1111/j.1466-8238.2011.00686.x CrossRefGoogle Scholar
  42. Kernohan BJ, Gitzen RA, Millspaugh JJ (2001) Analysis of animal space use and movements. In: Millspaugh JJ, Marzluff JM (eds) Radio tracking animal populations. Academic Press, San Diego, pp 125–166CrossRefGoogle Scholar
  43. Kovacs KM et al (2011) Global threats to pinnipeds. Mar Mammal Sci 28:414–436. doi: 10.1111/j.1748-7692.2011.00479.x CrossRefGoogle Scholar
  44. Laidre KL, Stirling I, Lowry LF, Wiig Ø, Heide-Jørgensen MP, Ferguson SH (2008) Quantifying the sensitivity of Arctic marine mammals to climate-induced habitat change. Ecol Appl 18:S97–S125. doi: 10.1890/06-0546.1 CrossRefPubMedGoogle Scholar
  45. Li WKW, McLaughlin FA, Lovejoy C, Carmack EC (2009) Smallest algae thrive as the Arctic ocean freshens. Science 326:539. doi: 10.1126/science.1179798 CrossRefPubMedGoogle Scholar
  46. MacArthur R, Recher H, Cody M (1966) On the relation between habitat selection and species diversity. Am Nat 100:319–332CrossRefGoogle Scholar
  47. Maslanik J, Stroeve J, Fowler C, Emery W (2011) Distribution and trends in Arctic sea ice age through spring 2011. Geophys Res Lett 38:L13502. doi: 10.1029/2011gl047735 CrossRefGoogle Scholar
  48. Miller S, Wilder J, Wilson RR (2015) Polar bear-grizzly bear interactions during the autumn open-water period in Alaska. J Mamm 96:1317–1325. doi: 10.1093/jmammal/gyv140 CrossRefGoogle Scholar
  49. Molnár PK, Derocher AE, Thiemann GW, Lewis MA (2010) Predicting survival, reproduction and abundance of polar bears under climate change. Biol Conserv 143:1612–1622CrossRefGoogle Scholar
  50. Molnár PK, Derocher AE, Thiemann GW, Lewis MA (2014) Corrigendum to ‘‘Predicting survival, reproduction and abundance of polar bears under climate change’’ [Biol Conserv 143 (2010) 1612–1622]. Biol Conserv 177:230–231CrossRefGoogle Scholar
  51. Monnett C, Gleason J (2006) Observations of mortality associated with extended open-water swimming by polar bears in the Alaskan Beaufort Sea. Polar Biol 29:681–687CrossRefGoogle Scholar
  52. Otis DL, White GC (1999) Autocorrelation of location estimates and the analysis of radiotracking data. J Wildl Manag 63:1039–1044CrossRefGoogle Scholar
  53. Pagano AM, Durner GM, Amstrup SC, Simac KS, York GS (2012) Long-distance swimming by polar bears (Ursus maritimus) of the southern Beaufort Sea during years of extensive open water. Can J Zool 90:663–676CrossRefGoogle Scholar
  54. Parkinson CL (2014) Spatially mapped reductions in the length of the Arctic sea ice season. Geophys Res Lett 41:4316–4322CrossRefPubMedPubMedCentralGoogle Scholar
  55. Parkinson CL, Comiso JC (2012) On the 2012 record low Arctic sea ice cover: combined impact of preconditioning and an August storm. Geophys Res Lett 40:1356–1361. doi: 10.1002/grl.50349 CrossRefGoogle Scholar
  56. Parmesan C (2006) Ecological and evolutionary responses to recent climate change. Annu Rev Ecol Syst 37:637–669. doi: 10.1146/annurev.ecolsys.37.091305.110100 CrossRefGoogle Scholar
  57. Parmesan C, Yohe G (2003) A globally coherent fingerprint of climate change impacts across natural systems. Nature 421:37–42. doi: 10.1038/nature01286 CrossRefPubMedGoogle Scholar
  58. Parmesan C, Burrows MT, Duarte CM, Poloczanska ES, Richardson AJ, Schoeman DS, Singer MC (2013) Beyond climate change attribution in conservation and ecological research. Ecol Lett 16:58–71. doi: 10.1111/ele.12098 CrossRefPubMedGoogle Scholar
  59. Perry AL, Low PJ, Ellis JR, Reynolds JD (2005) Climate change and distribution shifts in marine fishes. Science 308:1912–1915. doi: 10.1126/science.1111322 CrossRefPubMedGoogle Scholar
  60. Peterson AT, Sanchez-Cordero V, Soberon J, Bartley J, Buddemeier RW, Navarro-Siguenza AG (2001) Effects of global climate change on geographic distributions of Mexican Cracidae. Ecol Model 144:21–30. doi: 10.1016/s0304-3800(01)00345-3 CrossRefGoogle Scholar
  61. Pilfold NW, Derocher AE, Stirling I, Richardson E, Andriashek D (2012) Age and sex composition of seals killed by polar bears in the eastern Beaufort Sea. PLoS ONE 7:e41429. doi: 10.1371/journal.pone.0041429 CrossRefPubMedPubMedCentralGoogle Scholar
  62. Pilfold NW, Derocher AE, Richardson E (2014) Influence of intraspecific competition on the distribution of a wide-ranging, non-territorial carnivore. Glob Ecol Biogeogr 43:425–435CrossRefGoogle Scholar
  63. Pilfold NW, McCall A, Derocher AE, Lunn NJ, Richardson E (2016) Migratory response of polar bears to sea ice loss: to swim or not to swim. Ecography 39:001–011. doi: 10.1111/ecog.02109 CrossRefGoogle Scholar
  64. Ragen TJ, Huntington HP, Hovelsrud GK (2008) Conservation of Arctic marine mammals faced with climate change. Ecol Appl 18:S166–S174. doi: 10.1890/06-0734.1 CrossRefPubMedGoogle Scholar
  65. Ramsay MA, Stirling I (1988) Reproductive biology and ecology of female polar bears (Ursus maritimus). J Zool 214:601–633CrossRefGoogle Scholar
  66. Regehr EV, Hunter CM, Caswell H, Amstrup SC, Stirling I (2010) Survival and breeding of polar bears in the southern Beaufort Sea in relation to sea ice. J Anim Ecol 79:117–127CrossRefPubMedGoogle Scholar
  67. Rode KD, Amstrup SC, Regehr EV (2010) Reduced body size and cub recruitment in polar bears associated with sea ice decline. Ecol Appl 20:768–782. doi: 10.1890/08-1036.1 CrossRefPubMedGoogle Scholar
  68. Rode KD, Wilson RR, Regehr EV, St Martin M, Douglas DC, Olson J (2015) Increased land use by Chukchi Sea polar bears in relation to changing sea ice conditions. PLoS ONE 10:e0142213. doi: 10.1371/journal.pone.0142213 CrossRefPubMedPubMedCentralGoogle Scholar
  69. Rogers MC, Peacock E, Simac K, O’Dell MB, Welker JM (2015) Diet of female polar bears in the southern Beaufort Sea of Alaska: evidence for an emerging alternative foraging strategy in response to environmental change. Polar Biol 38:1035–1047. doi: 10.1007/s00300-015-1665-4 CrossRefGoogle Scholar
  70. Rosenzweig ML (1991) Habitat selection and population interactions: the search for mechanism. Am Nat 137:S5–S28CrossRefGoogle Scholar
  71. Schliebe S, Rode K, Gleason J, Wilder J, Proffitt K, Evans T, Miller S (2008) Effects of sea ice extent and food availability on spatial and temporal distribution of polar bears during the fall open-water period in the southern Beaufort Sea. Polar Biol 31:999–1010CrossRefGoogle Scholar
  72. Serreze MC et al (2000) Observational evidence of recent change in the northern high-latitude environment. Clim Change 46:159–207CrossRefGoogle Scholar
  73. Serreze MC, Holland MM, Stroeve J (2007) Perspectives on the Arctic’s shrinking sea-ice cover. Science 315:1533–1536. doi: 10.1126/science.1139426 CrossRefPubMedGoogle Scholar
  74. Smith TG (1980) Polar bear predation of ringed and bearded seals in the land-fast sea ice habitat. Can J Zool 58:2201–2209CrossRefGoogle Scholar
  75. Southwood TRE (1977) Habitat, the templet for ecological strategies? J Anim Ecol 46:337–365CrossRefGoogle Scholar
  76. Stirling I (2002) Polar bears and seals in the eastern Beaufort Sea and Amundsen Gulf: a synthesis of population trends and ecological relationships over three decades. Arctic 55:59–76CrossRefGoogle Scholar
  77. Stirling I, Archibald WR (1977) Aspects of predation of seals by polar bears. J Fish Res Board Can 34:1126–1129CrossRefGoogle Scholar
  78. Stirling I, Lunn NJ (1997) Environmental fluctuations in Arctic marine ecosystems as reflected by variability in reproduction of polar bears and ringed seals. In: Woodin SJ, Marquiss M (eds) Ecology of Arctic environments. Blackwell Science, EdmontonGoogle Scholar
  79. Stirling I, Spencer C, Andriashek D (1989) Immobilization of polar bears (Ursus maritimus) with telazol in the Canadian Arctic. J Wildl Dis 25:159–168CrossRefPubMedGoogle Scholar
  80. Stirling I, Andriashek D, Calvert W (1993) Habitat preferences of polar bears in the western Canadian Arctic in late winter and spring. Polar Record 29:13–24CrossRefGoogle Scholar
  81. Stirling I, Richardson E, Thiemann GW, Derocher AE (2008) Unusual predation attempts of polar bears on ringed seals in the southern Beaufort Sea: possible significance of changing spring ice conditions. Arctic 61:14–22CrossRefGoogle Scholar
  82. Stroeve J et al (2008) Arctic sea ice extent plummets in 2007. EOS 89:13–20CrossRefGoogle Scholar
  83. Stroeve J, Serreze M, Holland M, Kay J, Malanik J, Barrett A (2012) The Arctic’s rapidly shrinking sea ice cover: a research synthesis. Clim Change 110:1005–1027. doi: 10.1007/s10584-011-0101-1 CrossRefGoogle Scholar
  84. Stroeve JC, Markus T, Boisvert L, Miller J, Barrett A (2014) Changes in Arctic melt season and implications for sea ice loss. Geophys Res Lett 41:1216–1225CrossRefGoogle Scholar
  85. Swihart RK, Slade NA (1985) Testing for independence of observations in animal movements. Ecology 66:1176–1184CrossRefGoogle Scholar
  86. Thiemann GW, Iverson SJ, Stirling I (2008) Polar bear diets and Arctic marine food webs: insights from fatty acid analysis. Ecol Monogr 78:591–613CrossRefGoogle Scholar
  87. Tynan CT, DeMaster DP (1997) Observations and predictions of Arctic climatic change: potential effects on marine mammals. Arctic 50:308CrossRefGoogle Scholar
  88. Van Winkle W (1975) Comparison of several probabilistic home range models. J Wildl Manag 39:118–123CrossRefGoogle Scholar
  89. Walther GR et al (2002) Ecological responses to recent climate change. Nature 416:389–395. doi: 10.1038/416389a CrossRefPubMedGoogle Scholar
  90. Wang M, Overland JE (2009) A sea ice free summer Arctic within 30 years? Geophys Res Lett 36:L07502. doi: 10.1029/2009gl037820 Google Scholar
  91. Worton BJ (1987) A review of models of home range for animal movement. Ecol Model 38:277–298CrossRefGoogle Scholar
  92. Zhang X, Walsh JE (2006) Toward a seasonally ice-covered Arctic ocean: scenarios from the IPCC AR2 model simulations. J Clim 19:1730–1747CrossRefGoogle Scholar
  93. Zhang J, Spitz YH, Steele M, Ashjian C, Campbell R, Berline L, Matrai P (2010) Modeling the impact of declining sea ice on the Arctic marine planktonic ecosystem. J Geophys Res Oceans 115:C10015. doi: 10.1029/2009jc005387 CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.Department of Biological SciencesUniversity of AlbertaEdmontonCanada
  2. 2.Department of Environment and Natural ResourcesGovernment of Northwest TerritoriesInuvikCanada

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