Global Warming Effects | Polar Bear | Polar Bears on Fasting
The Polar Bear (Ursus maritimus) is a bear native to the Arctic Ocean and its surrounding seas. Being the world’s largest carnivore found on land, together with the Kodiak Bear they constitute the largest members of the Bear family. The polar bear is often regarded as a marine mammal because it spends many months of the year at sea. Polar Bears’ preferred habitat is the annual sea ice covering the waters over the continental shelf and the Arctic inter-island archipelagos.
These areas, known as the “Arctic ring of life”, have high biological productivity in comparison to the deep waters of the high Arctic. The polar bear tends to frequent areas where sea ice meets water, such as polynyas and leads (temporary stretches of open water in Arctic ice), to hunt the seals that make up most of its diet. Polar Bears are therefore found primarily along the perimeter of the polar ice pack.
For thousands of years, Polar Bear has been a key figure in the material, spiritual, and cultural life of Arctic indigenous peoples, and the hunting of polar bears remains important in their cultures. The debate over the bears had become one of the most heated environmental issues of recent years. Advocacy groups had called for the bears to be protected, not from hunters or developers, but on the grounds that their habitat was threatened by global warming.
The International Union for Conservation of Nature now lists global warming as the most significant threat to the polar bear, primarily because the melting of its sea ice habitat reduces its ability to find sufficient food, forcing them to go on fast. Polar Bears use sea ice as a hunting platform, catching seals by sitting next to their breathing holes and waiting to pounce. Spring is usually a time of feasting and not fasting for polar bears, filling up before summer when the ice retreats. What’s more, the early melting may also be resulting in a lack of prey. Sea ice is important to seals because they build dens for their pups in the overlying snow.
Environmental advocates said, “The rapid warming of the Arctic and melting of the sea ice pose an overwhelming threat to the polar bear, already suffering starvation/fasting, drowning and population declines as its sea-ice habitat melts away.” Warmer temperatures and earlier melting of sea ice are causing polar bears to go hungry/fasting. The number of undernourished bears has tripled in a 20-year period.
Insufficient nourishment leads to lower reproductive rates in adult females and lower survival rates in cubs and juvenile bears, in addition to poorer body condition in bears of all ages.
Seth Cherry of the University of Alberta, Canada, and colleagues monitored the health of polar bears in the ice-covered Beaufort Sea region of the Arctic during April and May in 1985, 1986, 2005 and 2006.
They immobilized the bears using tranquillizer darts and measured the ratio of urea to creatinine in their blood. A low ratio means that nitrogenous waste material is being recycled within the body and indicates the animal is fasting – a state which usually only occurs temporarily in males during the spring breeding season. Cherry’s team believes that the increase in fasting bears is explained by warmer temperatures and earlier spring melts
Anecdotal evidence backs up the team’s conclusions, with many more sightings of polar bears swimming in open water and resorting to eating other food, such as fish.
