Obbard, M. E. et al. Re-assessing abundance of Southern Hudson Bay polar bears by aerial survey: effects of climate change at the southern edge of the range. Arctic Sci. 4, 634–655 (2018). Ingolfsson, O. & Wiig, Ø. Late Pleistocene fossil find in Svalbard: the oldest remains of a polar bear ( Ursus maritimus Phipps, 1744) ever discovered. Polar Res. 28, 455–462 (2008). a b c Hailer, F.; Kutschera, V. E.; Hallstrom, B. M.; Klassert, D.; Fain, S. R.; Leonard, J. A.; Arnason, U.; Janke, A. (2012). "Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage". Science. 336 (6079): 344–347. Bibcode: 2012Sci...336..344H. doi: 10.1126/science.1216424. hdl: 10261/58578. PMID 22517859. S2CID 12671275. McNutt, J. W. & Gusset, M. Declining body size in an endangered large mammal. Biol. J. Linn. Soc. 105, 8–12 (2012).

a b Ramsay, M. A.; Stirling, I. (1986). "On the mating system of polar bears". Canadian Journal of Zoology. 64 (10): 2142–2151. doi: 10.1139/z86-329.

Help ensure the polar bear's future.

Inupiat wildlife guide Robert Thompson says he rarely walks around the village unarmed, especially at night.

Boonstra, R.; Bodner, K.; Bosson, C.; Delehanty, B.; Richardson, E. S.; Lunn, N. J.; Derocher, A. E.; Molnár, P. K. (2020). "The stress of Arctic warming on polar bears". Global Change Biology. 26 (8): 4197–4214. Bibcode: 2020GCBio..26.4197B. doi: 10.1111/gcb.15142. PMID 32364624. S2CID 218492928. When the sea ice melts, polar bears, particularly subadults, conflict with humans over resources on land. [171] They are attracted to the smell of human-made foods, particularly at garbage dumps and may be shot when they encroach on private property. [172] In Churchill, Manitoba, local authorities maintain a " polar bear jail" where nuisance bears are held until the sea ice freezes again. [173] Climate change has increased conflicts between the two species. [171] Over 50 polar bears swarmed a town in Novaya Zemlya in February 2019, leading local authorities to declare a state of emergency. [174] Mathewson, P. D. & Porter, W. P. Simulating polar bear energetics during a seasonal fast using a mechanistic model. PLoS ONE 8, e72863 (2013). Green, P. A.; Van Valkenburgh, B.; Pang, B.; Bird, B.; Rowe, T.; Curtis, A. (2012). "Respiratory and olfactory turbinal size in canid and arctoid carnivorans". Journal of Anatomy. 221 (6): 609–621. doi: 10.1111/j.1469-7580.2012.01570.x. PMC 3512284. PMID 23035637.Upon finding a female, a male will try to isolate and guard her. Courtship can be somewhat aggressive, and a male will pursue a female if she tries to run away. It can take days for the male to mate with the female which induces ovulation. After their first copulation, the couple bond. Undisturbed polar bear pairings typically last around two weeks during which they will sleep together and mate multiple times. [120] Competition for mates can be intense and this has led to sexual selection for bigger males. Polar bear males often have scars from fighting. [116] [117] A male and female that have already bonded will flee together when another male arrives. [121] A female mates with multiple males in a season and a single litter can have more than one father. [119] Polar bear cubs

Marine mammals are aquatic mammals that rely on the ocean and other marine ecosystems for their existence. They include animals such as cetaceans ( whales, dolphins and porpoises), pinnipeds ( seals, sea lions and walruses), sirenians ( manatees and dugongs), sea otters and polar bears. They are an informal group, unified only by their reliance on marine environments for feeding and survival. Fetterer, F., Knowles, K., Meier, W. & Savoie, M. Sea Ice Index (National Snow and Ice Data Center, 2002). Amstrup, S. C.; Marcot, B. G.; Douglas, D. C. (2008). "A Bayesian network modeling approach to forecasting the 21st century worldwide status of polar bears". Geophysical Monograph Series. 180. doi: 10.1029/180GM14. As other bears head out onto the ice and begin to gorge on seals, those females rest in the warm, dark dens, where they give birth in the winter and emerge with their cubs in the spring. They eat as much as they can in the spring so they can survive the summer shortfall and wait for sea ice to form anew the following fall, as the cycle begins again. In the book , Brother is wearing a red short sleeve with blue pants, on the show he was only seen wearing red and white trunksKay, J. E. et al. The Community Earth System Model (CESM) Large Ensemble Project: a community resource for studying climate change in the presence of internal climate variability. Bull. Am. Meteorol. Soc. 96, 1333–1349 (2015).

a b Wemmer, C.; Von Ebers, M.; Scow, K. (1976). "An analysis of the chuffing vocalization in the polar bear ( Ursus maritimus)". Journal of Zoology. 180 (3): 425–439. doi: 10.1111/j.1469-7998.1976.tb04686.x. Stirling, I., Lunn, N. J. & Iacozza, J. Long-term trends in the population ecology of polar bears in western Hudson Bay in relation to climate change. Arctic 52, 294–306 (1999). In the Svalbard region, sea ice is constantly being pushed away from shore by currents, and so, when summer arrives and new ice is no longer being formed, some of the so-called pelagic bears may find themselves trapped on or near land as the sea ice drifts away; come fall, they will be waiting anxiously for the ice to re-form so they can once more set out far from shore. Others, however, never leave the ice at all if they can avoid it. Kumar, V.; Lammers, F.; Bidon, T.; Pfenninger, M.; Kolter, L.; Nilsson, M. A.; Janke, A. (2017). "The evolutionary history of bears is characterized by gene flow across species". Scientific Reports. 7: 46487. Bibcode: 2017NatSR...746487K. doi: 10.1038/srep46487. PMC 5395953. PMID 28422140. Polar bears have prominent roles in Inuit culture and religion. The deity Torngarsuk is sometimes imagined as a giant polar bear. He resides underneath the sea floor in an underworld of the dead and has power over sea creatures. Kalaallit shamans would worship him through singing and dancing and were expected to be taken by him to the sea and consumed if he considered them worthy. Polar bears were also associated with the goddess Nuliajuk who was responsible for their creation, along with other sea creatures. It is believed that shamans could reach the Moon or the bottom of the ocean by riding on a guardian spirit in the form of a polar bear. Some folklore involves people turning into or disguising themselves as polar bears by donning their skins or the reverse, with polar bears removing their skins. In Inuit astronomy, the Pleiades star cluster is conceived of as a polar bear trapped by dogs while Orion's Belt, the Hyades and Aldebaran represent hunters, dogs and a wounded bear respectively. [193]

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a b Edwards, C. J.; Suchard, M. A.; Lemey, P.; Welch, J. J.; Barnes, I.; Fulton, T. L.; Barnett, R.; O'Connell, T.; Coxon, P.; Monaghan, N.; Valdiosera, C. E.; Lorenzen, E. D.; Willerslev, E.; Baryshnikov, G. F.; Rambaut, A.; Thomas, M. G.; Bradley, D. G.; Shapiro, B. (2011). "Ancient hybridization and an Irish origin for the modern polar bear matriline". Current Biology. 21 (15): 1251–1258. doi: 10.1016/j.cub.2011.05.058. PMC 4677796. PMID 21737280.