Polar bears (Ursus maritimus) are decreasing in many parts of their range, and many scientists are predicting that two-thirds of polar bears will be gone by mid-century.
Fragmentation and loss of sea-ice are the most critical conservation concerns for polar bears today. Polar regions have experienced significant warming in recent decades. Increased atmospheric concentrations of greenhouse gases are having a larger effect on climate in the Arctic than anywhere else on the globe. Warming has been most pronounced across the Arctic Ocean Basin and along the Antarctic Peninsula, with significant decreases in the extent and seasonal duration of sea-ice. Rapid retreat of glaciers and disintegration of ice sheets have also been documented. Arctic sea ice extent is now more than two million square kilometres less than it was in the late 20th century, and the duration and magnitude of the current decline in sea ice seem to be unprecedented for the past 1,450 years.
Polar bears are distributed throughout the circumpolar basin with the southern extent of the distribution limited by the extent of Arctic sea-ice. Their preferred habitat is the annual sea-ice over the continental shelf and inter-island archipelagos that encircle the polar basin. Sea-ice allows polar bears to exploit the productive marine environment by providing a platform from which they can hunt ringed and bearded seals and occasionally take belugas, narwhals, walrus, harbor seals, reindeer and birds, in an environment that has been largely free of competitors and predators, with the exception of humans in nearshore areas.
Polar bears show fidelity to geographic regions. They occupy multiannual home ranges outside of which they seldom venture. Not all areas of their multiannual home ranges are used each year. In areas of volatile ice, a large multiannual home range, of which only a portion is used in any one season or year, is an important part of the polar bear life history strategy.
During spring and summer polar bears in the Arctic archipelago use land-fast ice most intensively, whereas in Baffin Bay moving ice was a stronger preference. In autumn, female polar bears from both regions preferred multiyear ice. Differences were also apparent between the two regions for the distances of bears to the ice edge, as well the preference to closed ice. It is likely that further differences exist for each of the other regions. For instance, another study found that polar bears in the Beaufort Sea and Amundsen Gulf in the western Canadian Arctic preferred floe-edge, moving ice, and drifting fast-ice habitats in the late winter and spring.
Across most of their range, pregnant female polar bears excavate dens in snow and ice in early winter and give birth in those dens during midwinter, emerging in the spring when their cubs are approximately three months old. In some areas, notably the Beaufort and Chukchi Seas of the polar basin, many females den and give birth to their young on drifting pack ice.
Wild Migration Programme GoalWild Migration strives for a future where polar bear habitat loss has been slowed and where key sub-regions are stablised or recovering. Wild Migration Policy TargetWild Migration will strategically work towards a listing of polar bear on the CMS Appendices, at the 11th CMS Confernce of the Parties in recongistion of the urgent and globally shared responsiblity to protect polar bear habitat from climate change. |
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Wild Migration Projects contact details
RSD 426 Newland Service,
Via Kingscote, 5223, Australia
Phone: +618 8121 5841
Fax: +618 8125 5857
Email: projects[at]wildmigration.org
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