Polar bears and sea ice

Courtesy of Reanne Oberhelman:

Macroevolution.net is a scientific website made up of articles about human evolution, biology, marine biology, animals, and other topics in earth science. The word macroevolution is described as ‘the process producing new forms of life treated as distinct species’, which is what this site is dedicated to. A recent article on macroevolution.net titled, “Polar Bears Eating Goose Eggs” discusses Arctic polar bears and how they must adjust to the warming climate in order to survive.

Each spring, the Arctic thaws earlier and earlier than the year before providing polar bears with a different type of food in the Hudson Bay, goose eggs. Eating the goose eggs whole, or breaking the shells and then eating them, provides the polar bears with an alternative source of highly nutritious food as they come into contact with these goose nests.

Polar bears, or Ursus maritimus, are on the United States’ Endangered Species List as “a threatened species” because their population is declining, an issue that will increase as the climate gets warmer. Polar bears in the Arctic are known for hunting seals on the sea ice, but as this sea ice melts sooner each year, the polar bears are forced back onto land to live off their internal stored fat reserves. As they retreat to the tundra they come into contact with the nesting grounds of the snow geese. Fortunately, the population of snow geese in the Arctic is too high in the summer to be supported by the area, so the fact that polar bears are using them as an alternative source of food is a good thing, for the present time.

The rate of change of ice breakup has been calculated as .72 days earlier each year and present trends indicate that the arrival of polar bears will overlap the mean hatching period in 3.6 years. At this point, a polar bear must eat the eggs of 43 nests to make up for the average seal hunting day. A projection of ten years indicates that a bear would only need to consume the eggs of 34 nests because of timing changes. At this time, the embryos of the goose eggs are younger, and therefore more nutritious.

Because polar bears depend on the sea AND the ice to get their sources of food, will they become extinct as these climate changes continue; or will the polar bears be able to adapt like they have so far?