Polar bears generally use sea ice to hunt(捕猎), but a newly discovered group has found another way. An isolated(与世隔绝的) population of polar bears has been discovered in a fjord(峡湾) in southeast Greenland, which is free of sea ice for most of the year. Polar bear generally need sea ice to survive, so the discovery is raising hopes that some kinds of the polar bears might survive the loss of sea ice caused by global warming.
Researchers found the population living in a fjord in the southeast Greenland, which is surrounded by mountains and an ice sheet to the west, and ocean to the east. The sea-ice coverage lasts for only around 100 days each year. With sea ice in the fjord becoming smaller because of global warming, the whole group were expected to die out by the end of this century.
But the isolated population has found a way to hunt without sea ice. The group, about 27 adult females, has been isolated from other polar bear populations along Greenland's east coast for at least 200 years.
Tracking data from marked bears proves that they don't move far. For example, when members of the group went out of the fjord, the ice on which they sat sometimes got caught in the rapid water flow. "Whenever this happened, they would get stuck and then, they would have to jump off, swim to the beach and walk back home empty-handed," says lead author Kristin Laidre, an animal ecologist at the University of Washington in Seattle.
Though the researchers failed to video their hunting without sea ice, the existence of this small population in conditions of low sea-ice coverage suggests there is a chance that the population can survive, even as sea ice flows away to farther north each year.
