Which is a difference between “Turtle Eggs” and “Bear Beware”? Between July and mid-November, polar bears lounge on the shores of Hudson Bay, living off their own fat while they wait for the sea to freeze up. Once the ice is thick enough to support their thousand-pound bulk, the bears can resume hunting for seals, their main source of food. Since the early 1980s, the huge loafing bears have become an autumn tourist bonanza, attracting bus-size tundra vehicles full of curious bear-watchers. The balloon-tired vehicles sometimes come within 130 feet of the bears and stay near them for as long as two hours. Markus G. Dyck and Richard K. Baydack, wildlife biologists at the University of Manitoba in Winnipeg, recently confirmed that such tourism may be seriously disturbing the animals.