Polar Bear, Ursus maritimus
August 2009

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polar bear

(Agnarsson et al 2010) (Ingolfsson & Wiig 2008) (Krause et al 2008) (Yu et al 2007) (Lindquist et al 2010) (O'Brien 2003) (Schliebe et al 2006) (Wozencraft 2005) (Yu et al 2004) (Yu et al 2007) (ITIS 2010)

Describer (Date): Phipps (1774:p.185) A Voyage Towards North Pole, London: J. Nourse for Ursus maritimus

Kingdom: Animalia
    Phylum: Chordata
         Class: Mammalia
             Order: Carnivora (15 families)
                      Family: Ursidae (bears)
                                Genus: Ailuropoda (Giant Panda)
                                Genus: Helarctos (Sun Bear)
                                Genus: Melursus (Sloth Bear)
                                Genus: Tremarctos (Spectacled Bear)
                                Genus: Ursus (bears)
                                       Species: Ursus maritimus (Polar Bear)
                                       Species: Ursus americanus - American Black Bear
                                       Species: Ursus arctos - Brown Bear, Grizzly Bear
                                       Species: Ursus thibetanus - Asian Black Bear
Nomenclature Phylogeny (Yu et al 2007) (Yu et al 2004) (Schliebe et al 2006)
(Amstrup & Gardner 1994) (DeMaster & Stirling 1981) (Derocher et al 2004) (Durner et al 2006) (Stirling 1993) (Travis 1994)

  • Circumpolar distribution throughout Arctic.
  • Primary habitat: North Polar Basin, annual sea ice fields attached to shorelines.
  • Evolutionarily adapted to sea ice; most remain on ice year-round, spending only short periods on land (Only 7% of Polar Bears' time is spent on land, mostly in maternal dens). A few bears occupy permanent pack ice found in the central Arctic basin.
  • Not evenly distributed throughout range on sea ice; show preference for certain sea ice characteristics (Stirling 1993) and location (near continental shelf). (Derocher 2004)
  • Most abundant near shore (in shallow water areas) where currents increase marine productivity and keep the ice cover from becoming too consolidated in winter.
  • Cracks and holes in ice give polar bears access to seals coming up from water below.
  • Distribution in most areas varies seasonally with extent of sea ice cover and availability of prey.
  • Suitable sea ice cover has declined in last decades and the decline is accelerating. Sea ice breakup dates in 2004 were 3 weeks earlier than recorded in 1984. Vulnerable young and old bears are highly stressed under such conditions.
  • Polar Bear denning sites are critical for the survival of the cubs. Most dens are found near the coastlines, with the exception of the Hudson Bay area where they may den as far as 118 km (73 mi) inland; denning sites may also be located on drifting pack ice in many areas
  • Countries having Polar Bear populations:
    • United States (Wrangel Island, western Alaska, northern Alaska)
    • Canada (Manitoba, Newfoundland, Labrador, Nunavut, Northwest Territories, Quebec, Yukon Territory, Ontario)
    • Denmark/Greenland
    • Russian Federation
    • Norway (plus Svalbard-Franz Josef Land)

Click on map to see a larger image.

(Amstrup 2003) (Cushing et al 1988) (DeMaster & Stirling 1981) (Derocher et al 2005) (Kurt 1990)
(Nachtigall et al 2007) (Stirling 1993, 1998)
Pelage and Skin
(Atkinson & Ramsay 1995) (Cushing et al 1988) (DeMaster & Stirling 1981) (Derocher 2010) (Durner et al. 2011) (Ferguson et al 2000) (Folk et al 1976) (Folk et al 1980) (Ginsburg 1994) (Gittleman 1989) (Herrington 1963, 1968) (Jonkel et al 1972) (Kurt 1990) (McGee-Lawrence et al 2008) (Megan 2009)(Messier et al 1994) (Nowak 1981) (Owen 2009) (Schweinsburg 1979) (Stirling 1993, 1998) (Van de Velde et al 2003) (Watts and Hansen 1987) (Welch et al. 2014) (Wemmer 1976)

Activity Cycle

        Daily Pattern
        Yearly pattern Social Group

      General       Aggression       Hunting       Territorial Behavior Communication

        Vocalization (Wemmer et al 1976; Cushing et al 1988)         Olfactory and visual signals        Locomotion Hibernation and denning Thermoregulation Interspecies Interaction (DeMaster & Stirling 1981) (Regehr et al 2007) (Rosing 2006) (Stirling 1977, 1993) (Amstrup 2003)
(Amstrup 2003) (Demaster & Stirling 1981) (Derocher et al 1993) (Derocher et al 2004) (Stirling 1993)

(Amstrup 2003) (Atkinson & Ramsay 1995) (Jenness et al 1972) (DeMaster & Stirling 1981) (Onorato et al. 2009) (Ramsey & Stirling 1986) (Stirling 1993) (Zeyl et al 2009)

Courtship: Reproductive rate: 3 years - females usually don't breed again until separation from young

Life Stages

        Birth: Late November / early January; most births occur by mid-December.

        Litter Size:         Infant:         Cubs         Adults        Longevity
(Brown 1993)
(Clubb & Vickery 2006) (ISIS Web Site) (Swaisgood & Shepherdson 2006)

(Aars et al 2006) (Amstrup 2003) (Dowsley 2007) (Molnar et al 2010) (Prestrud & Stirling 1994) (Schliebe et al 2006) (Stirling 1993) (Stirling and Derocher 2007) (Stirling et al 2008) (Servheen 1989) (IUCN 2009)
Threats to survival
Other Web Resources


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