Polar Bear Ecology

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The Arctic’s Iconic Carnivore

Abstract
Climate change effects on the arctic are now becoming more evident to ecologists. Severe declines in polar bear populations are more noticeable as periods of sea ice cover are steadily declining. A decrease in sea ice is leading to nutritional stress in polar bears due to shorter periods available in prime hunting grounds. As a necessity to the polar bear’s niche a loss of sea ice has harmful implications to polar bear populations. Not only are hunting grounds being lost but industrialization and human habitation are decreasing the size of the polar bear’s natural habitat.

The Arctic’s Iconic Carnivore

There is increasing evidence from around the world today to show global climate is changing at an unprecedented rate. Many of the studies showing this evidence have now shifted to the arctic. This is due to the fact that many arctic species live in a fragile balance with the ecosystem around them. One of these species is the polar bear, being the largest land carnivore of this current time it is hard to believe that this icon of the arctic and arctic survival is in need of help. Studies in many regions across the circumpolar nations show that polar bear populations are declining. In the coming years it will be up to human conservation efforts to save this icon of the arctic, if it is not already too late.

The polar bear is the symbol of power and determination to anyone who lives in the arctic. But the Inuit peoples across northern Canada see the polar bear as a way of life. It is the only way that they can sustain their families and themselves. Stirling and Parkinson explain that until recent years it was believed that unsustainable harvesting was the main factor threatening polar bear populations (2006, p.262). This seems like a faulty empirical claim at best when you take into consideration how much the Inuit depend on this animal for subsistence hunting, and the fact that they have been harvesting polar bears for thousands of years. It is time to look for other possibilities for the decline in the population of polar bear.

It is known that polar bears are dependent on arctic sea ice. They use the ice for many things like hunting, breeding and traveling from place to place. In recent years there have been studies showing that there is a decline in arctic sea ice, and a thinning of multiyear sea ice (Stirling et al., 2006, p.262). Because polar bears are so dependent on arctic sea ice, a shift towards a warmer climate resulting in a loss of sea ice will have big ecological impacts on the bears themselves. “The dependence of polar bears on arctic sea ice for access to seals, suggests their survival and breeding probabilities are linked to sea ice conditions” (Regehr et al., 2010, p.118). This quote tells us that the polar bear is so directly tied to sea ice that it will not be able to find mates successfully to create the next generation. It will also starve to death if the problem of declining arctic sea ice goes unchecked.

A changing climate brings even more detrimental problems for the polar bear. Along with changing sea ice the seasons which dictate the movement of the sea ice are now changing. This means that winter freeze up is now coming later in the season and winter break up is now coming sooner in the season. Because the polar bear does not use torpor as a survival strategy like most northern bears, they must survive all summer on fat reserves they stored up over winter. A large portion of polar bears move inland during break up to supplement their diet with anything they can find over summer months. Gleason et al, explain that because of a later freeze and earlier break up they have noticed that polar bears are coming ashore in the Hudson Bay area’s sooner and in worse conditions than has been seen in previous years (2009, p.406).

This seasonal change in the arctic has also brought the polar bear into closer contact with humans. “Longer ice free...
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