Polar bear mothers invest a huge amount into their cubs (幼兽), isolating themselves in dens (兽穴) dug with great effort into piles of snow to provide care through the unforgiving conditions of Arctic winter. It's little wonder that the bears are hesitant to leave when disturbed, even when oil drilling equipment is in operation nearby.
"We found that bears wouldn't abandon their dens even with vehicles driving right overhead," says Wesley Larson, who worked his way from office assistant to a graduate student position with Utah's Brigham Young University, monitoring polar bears on Alaska's North Slope.
Scientists have recorded an increase in human-wildlife conflict in the area, as offshore pack ice has decreased, forcing the bear population to create their dens closer to petrol industry activity. With increased industry interest in oil and gas leasing (租赁) in the Arctic National Wildlife Refuge, strong evidence to help support and carry out protective measures for the species has never been more important.
Wildlife managers in Alaska depend on a rule that industrial activity and research cannot take place within 1. 6 km of a den with newborn babies in it. Working with 15 years of monitoring records, and 30 years of notes concerning interactions between the industry and the bears, Larson and colleagues were able to confirm that the regulation was sufficient, but that more needed to be done to actively locate dens. He explains that with entrances quickly covered by snow and dens closed-up until spring, they are effectively undetectable to the naked eye.
"While technology such as forward-looking infrared cameras can be used to try to pick up a heat signature inside the den, it only works when conditions are perfect, and they rarely are in Arctic winter," says Larson. He is now consulting on a project using radar technology to identify dens and ensure protection for the animals symbolic of the Arctic.