Shrinking polar bears

Climate change and pollution cause stress. Because of this stress polar bears are getting smaller. Danish researchers concluded this after an extensive examination of polar bear skulls.
The scientists examined three hundred polar bear skulls from the previous century. The skulls from the second half of the twentieth century were 2 to 9 percent smaller than those from the beginning of the twentieth century. The skulls also had a different shape. According to the researchers the skulls are smaller because the sea ice is melting. The area where the bear can hunt is getting smaller and smaller. Because of this, the bears need to use an increased amount energy to hunt. This leaves the bear with less energy for growth.

The altered shape of the skulls may be the result of stress that is caused by pollution. But also the increased occurrence of inbreeding, due to the decreased number of polar bears, may be a cause of this.

The result of the research were published in the Journal of Zoology.