Polar bearsby | 15-05-2013 19:41 |
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 Today I attended a lecture on how climate change and other factors are affecting the polar bears adversely. These are some of the notes I took. . The polar bear, also known as the white bear, northern bear, or sea bear, is a large bear native to the Arctic. It is one of the two largest land carnivore species and the top predator within its area. It is well adapted to its habitat: it has thick blubber and fur to insulate to it against the cold as well as white colored fur that camouflages it from its prey. The polar bear hunts well on land, on the sea ice, as well as in the water. The polar bear is a circumpolar species found in and around the Arctic Ocean whose southern range limits are determined by pack ice. Their southernmost point is James Bay in Canada. While their numbers thin north, there is evidence of polar bears all the way across the Arctic. Population estimates are generally just over 20,000. The destruction of its habitat on the Arctic ice, which has been attributed to global warming, threatens the bear's survival as a species it may become extinct within the century. Signs of this have already been observed at the southern edges of its range. . The key danger posed by climate change is malnutrition or starvation due to habitat loss. Polar bears hunt seals from a platform of sea ice. Rising temperatures cause the sea ice to melt earlier in the year, driving the bears to shore before they have built sufficient fat reserves to survive the period of scarce food in the late summer and early fall.. . Polar bears accumulate high levels of persistent organic pollutants such as polychlorinated biphenyl (PCBs) and chlorinated pesticides. Due to their position at the top of the food pyramid, with a diet heavy in blubber in which halocarbons concentrate, their bodies are among the most contaminated of Arctic mammals. |
