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Animal of the Month: Eight ways climate change affects polar bears

An icon of the Arctic, the polar bear is a fairly common sight in the news, whether it’s because the polar ice caps are melting or because of a cute new arrival at a zoo. But how exactly has habitat loss and climate change affected the well being of polar bears?

Now classified as a vulnerable species, we will be celebrating the polar bear this month while also raising awareness of the species’ decline with these eight facts about polar bears and climate change.

1. Stressed out
The livelihood of many Arctic species is dependent on the ice, most notably the polar bear. However, due to the dramatic decrease in the area and thickness of polar ice, polar bear populations are decreasing in size and the polar bears themselves are becoming increasingly stressed.

2. Dieting isn’t designed for polar bears
In areas where sea ice has reduced, polar bears have restricted access to prey, especially during summer when the sea ice declines even further. As a result of polar bears fasting for longer and depleting their fat stores due to this, adult polar bears now weigh less than they did a decade ago.

3. Dieting especially isn’t designed for pregnant polar bears and their offspring
Female polar bears – especially those who are pregnant – experience a period of hibernation and fasting. Polar bears that have been required to fast prior to this period due to a lack of access to food are less likely to be able to produce cubs or provide them with milk when they are born.

4. No food, no gains
The longer period of summer fasting that polar bears have to experience increases the risk of muscle atrophy, or wastage, occurring. This consequently reduces their ability to travel and hunt, making recovery from fasting more difficult.

Image credit: Endangered arctic – starving polar bear by AWeith. CC BY-SA 4.0 via Wikimedia Commons.

5. Geese make for a filling meal
You may not consider geese a vital part of the polar bear diet, but they could become an increasingly important resource as the bears are forced to spend more time on land. Polar bears have often been observed chasing snow geese (as well as other land animals), and it has been found that the nutritional benefits outweigh the energy costs of the chase.

6. Grizzly competition
Due to the increased period of time spent on land, polar bears encounter competition for food from grizzly bears. Despite being twice the size of their grizzly counterparts, polar bears are often chased away from whale carcasses by the native grizzly bears. However, female polar bears with cubs are more likely to act aggressively towards the grizzlies in response to the competition.

7. Hunted
Around 700 polar bears are hunted per year, mainly by indigenous people. Although this in itself isn’t a threat to the species as a whole, hunting is regulated due to the slow population growth caused by global warming and increasing levels of pollution.

8. Could blueberries solve polar bears’ dieting troubles?
During ice-free season polar bears must hunt on land, and this period is getting longer due to global warming. Scavenging, not only hunting, can provide polar bears with food: bears who weigh up to 280kg are able to match their daily energy loss by eating blueberries as a substitute for their primary prey of seals.

Featured image credit: Polar bear (Ursus) maritimus female with its cub, Svalbard by AWeith. CC BY-SA 4.0 via Wikimedia Commons.

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