In casual encounters with the material universe, we rarely feel any difficulty here, since we usually deal with things that are clearly alive, such as a dog or a rattlesnake; or with things that are clearly nonalive, such as a brick or a typewriter. Nevertheless, the task of defining "life" is both difficult and subtle; something that at once becomes evident if we stop to think. Consider a caterpillar crawling over a rock. The caterpillar is alive, but the rock is not; as you guess at once, since the caterpillar is moving and the rock is not.
Myth Busters Seasonal Changes Polar bears respond to seasonal changes and the distribution of seals and sea ice. In food-rich areas, they have smaller home ranges and their habitat often overlaps with other bears. Scientists believe that most polar bears limit travel to home ranges of a few hundred miles.
However, they know of one satellite-tracked female that trekked 4, kilometers —from Alaska's Prudhoe Bay to Greenland to Canada's Ellesmere Island and back to Greenland. The Four Sea Ice Regions Polar bears need a platform of sea ice to more easily reach their seal prey.
But, not all sea ice is equal. Governments and scientists have designated 19 populations of polar bears based in four different sea ice regions in the Arctic. These sea ice regions function as distinct management units and are spread out among five countries: The following four sea ice eco-regions differ in geography, status, sea ice levels, and vulnerability to climate change.
Seasonal Ice Baffin Bay, Davis Strait, Foxe Basin, Southern Hudson Bay, and Western Hudson Bay Seasonal ice areas occur at the southern extreme of the polar bear's range and include places like Canada's Hudson Bay, where the ice melts completely each summer and the bears must wait for freeze-up in the fall until they can hunt again.
Status of these populations: Polar bears in seasonal ice areas are the most endangered, with longer and longer ice-free seasons testing the limits of their fat reserves. As the sea ice retreats farther and farther from shore in a warming Arctic, these polar bears are faced with a choice of coming ashore—and fasting until the ice returns in the fall—or swimming long, exhausting distances to reach the remaining pack ice.
However, because ice located far offshore lies over less productive waters, bears in these areas may successfully complete a marathon swim yet still not find any seals to hunt.
Polar bears that live in these areas are at great risk—from longer and longer swims, prolonged fasting periods, and encounters with humans on shore. Polar Basin Convergent Ice Eastern Greenland, Northern Beaufort Sea, and the Queen Elizabeth Islands Sea ice formed locally and transported from other parts of the Arctic collects along the shore of these habitats, providing polar bears with access to seals over productive waters.
Polar bears in these areas are faring well now, but scientists predict that ice in these areas will disappear within 75 years—and, with it, resident polar bear populations—unless action is taken to reduce carbon emissions.
This ecoregion is likely to provide a last refuge for polar bears and their sea-ice prey, but ultimately it too is threatened, without action on climate change.
Why does it help to divide the Arctic into sea ice regions? It allows scientists to make informed estimates about how a population is faring, based on the health and condition of well-studied populations within the same region or across various regions.
Here we take a look at the way polar bears make their moves across the sea ice.
Females with small cubs walk more slowly, about two-and-a-half to four kilometers per hour. Polar bears are able to gallop as fast as a horse over short distances but prefer to amble leisurely. Norwegian scientist Nils Oritsland showed us that polar bears expend more than twice the energy of most other mammals when walking or running, showing higher-than-average increases in temperature and in oxygen consumption.
Walking bears expend 13 times more energy than resting bears. This partly explains their preference for still-hunting, which usually involves a long, patient wait for a seal to surface at a breathing hole in the sea ice.
Natural Sprinters Polar bears are natural sprinters and can run as fast as 40 kilometers per hour—but only for short distances. Younger, leaner bears are the best runners.
They can cover two kilometers without stopping, whereas older, larger bears will quickly overheat.Polar Bears and their Retreating Habitat Essay – Include the scientific and common names of your species The Polar bears scientific name is Ursus maritimus, which means quot;maritime bear quot;.
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Essay about Polar Bears and their Retreating Habitat Words 5 Pages Some of the risk factors that contribute to its registration on the Species At Risk Public Registry are hunting, reduction of availability of their prey, the reduction of their melting sea ice, and pollution, but mainly human actions.
Although polar bears are white, you have brought up two very grey-area topics. First, there's the whole question of "global warming." The phrase "global warming" is mentioned so often that it's. ASSISTED COLONIZATION is the intentional movement and release of an organism outside its indigenous range to avoid extinction of populations of the focal species..
ECOLOGICAL REPLACEMENT is the intentional movement and release of an organism outside its indigenous range to perform a specific ecological function.. See the 3-fold chart immediately below for distinctions between three forms of.
"Polar bears rely almost entirely on the marine sea ice environment for their survival so that large scale changes in their habitat will impact the population (Derocher et al.
). Global climate change posses a substantial threat to the habitat of polar bears. Essay about Polar Bears and their Retreating Habitat Words 5 Pages Some of the risk factors that contribute to its registration on the Species At Risk Public Registry are hunting, reduction of availability of their prey, the reduction of their melting sea ice, and pollution, but mainly human actions.