Cosewic assessment update status report polar bear

West: Western portion only, excluding the Quebec section. NWT animals have adapted to short intense summers and long periods of snow cover by migrating, hibernating or changing behaviour and food sources to optimize survival and reproduction. Plants have adapted to fire, short intense growing seasons and long cold, dry winters. Changes in temperature, snow cover and the length of the growing and snow seasons will have an impact on wildlife behaviour and growth patterns, and, ultimately, on their distribution and survival.

Species previously not capable of surving in our ecosystems may find new habitats in the NWT if snow seasons become less severe and growing seasons are longer. The effects of change in our climate on biodiversity are being tracked. Studies show some changes are measureable but subtle. Other studies show a warming climate is enhancing, in a cumulative fashion, the effect of other changes in land use and disturbance on our biodiversity.

A summary of current findings is presented here. Permafrost is degrading and altering vegetation by creating disturbed areas that are nutrient rich, which enhances growth of green alders. Thaw slumps resulting from permafrost degradation are increasing 2 and can accelerate the effects of climate change on tundra vegetation 3. Warm Winters and Parasites Warming is changing the ecology of parasites already in the North and facilitating invasion of new parasites from elsewhere 4.

A mismatch between breeding and availability of food for some species of migratory birds nesting in the Arctic and boreal forest is thought to be the main cause of declines in populations Auk These changes are predicted by climate change scenarios and are part of a trend toward spring warming and earlier snow melt observed in the northern hemisphere 1, The rate of change in temperature and precipitation is faster than climate change models predictions.

Normal climatic variations do not fully explain these warming winters and changes in precipitation. There is evidence natural climate fluctuations, such El Nino, enhances the effects of continued warming in the Arctic causing, in some years, rapid and less predictable changes in northern ecosystems, such as a record low in Arctic sea ice in September The actual growing season is different for different plant species.

The relative changes in the start, end and length of the growing season, however, are relevant to all species and ecosystems 1. See Climate Research Division study for details in statistical procedures 1. The trend analyses are based on weather stations in the entire ecozone in Canada, including some in the NWT.

The number of stations used for analysis are for each ecozone, for growing season gs and snow season Snow : Arctic: 20 gs ; 26 snow , Taiga Shield West: 5 gs ; 0 snow , Taiga Plains: 6 gs , 11 snow ; Taiga Cordillera: 1 gs , 0 snow.

Found an error or have a question? Climate Research Division, Environment Canada. Geophysical Research Letters L Kokelj, S. Gergel, and G. Relative impacts of disturbance and temperature: persistent changes in microenvironment and vegetation in retrogressive thaw slumps. Full description of Spotted Wolffish. Conservation commitment on the boreal caribou: Val-d'Or population.

Summary of the imminent threat analysis for southern mountain caribou. Applications now open for federal government environmental funding programs. The bears return to the sea ice in the fall when freeze-up occurs. Pregnant females excavate maternity dens in which to give birth, generally on land near the coast. Dens are dug in snowdrifts or, in areas farther south, in frozen earth or peat. They are often located near areas where there are high densities of seals in the spring.

In the Beaufort Sea western part of the Canadian Arctic maternity dens are sometimes observed on drifting pack ice. During the winter, the pregnant females remain sheltered in their dens, whereas the other bears are active on the pack ice.

These animals, which are well adapted to the Arctic, also use shelter dens during very harsh weather. Such dens can be found km or more offshore.

By altering the extent of the sea ice and the distribution of the seals that reproduce on the sea ice, climate warming will definitely have an impact on the distribution of Polar Bears. Females reach reproductive maturity at about 4 to 6 years of age and typically have litters of one or two cubs about every three years. Most males begin to breed at about 8 to 10 years of age. Few Polar Bears live longer than 25 years. Mating takes place in late April or early May, but implantation of the fertilized egg does not occur until October.

Pregnant females enter maternity dens in late October and the young are born between November and early January. At birth, cubs weigh less than 1 kg and are covered in very fine hair.

They are nursed inside the den until some time between the end of February and the middle of April, when they venture out on the sea ice with their mother. By this time, the cubs weigh 10 to 12 kg.

Pregnant females spend a large part of the winter in their dens without feeding, and they cannot end their fast until their young are old enough to be moved from the den. As a result, these females may not eat for up to eight months but still have to meet the energetic demands of gestation and lactation. The Polar Bear is the most carnivorous of the bears. It generally does not attack humans, except to protect its young or when starving.

It feeds primarily on ringed seals but may also eat bearded seals, harp seals, hooded seals, harbour seals and sometimes young walruses, belugas and narwhals.

During the summer, bears that remain on land live mainly on their fat reserves and conserve their energy by remaining inactive most of the time. They occasionally eat grass and berries. The Polar Bear has no natural predators. However, as an apex predator i. The bears themselves may build up environmental contaminants in their tissues that can affect their survival and reproduction. Compared to other terrestrial mammals, Polar Bears travel over exceedingly large areas.

They readily adapt their movements to environmental conditions and the availability of prey species, and they can be sensitive to human activity. Nevertheless, these bears are known to use non-natural sources of food, such as garbage, and they may become habituated to the presence of humans, despite attempts to scare them away, if food rewards can still be obtained. The following is a list of current threats facing the Polar Bear. It is recognized that the relative impact of these threats on Polar Bears may change, and that new threats may be identified in the future.

Climate change: Environmental change is the most critical long-term threat to Polar Bears and their habitat. Projected warming over much of their range and the associated reductions in the extent and thickness of multi-year sea ice, and the duration and thickness of annual sea ice, will have both direct and indirect effects on Polar Bears.

Direct effects include change of habitat i. Climate change is likely to influence all of the threats listed below for the Canadian population and it should therefore be treated as the ultimate limiting factor for the species. The observed declines in the Western Hudson Bay and Southern Beaufort Sea management units can largely be attributed to climate change.

Changes in sea ice are not expected to affect Polar Bears in all portions of their range at the same time, or in the same ways.