The following is an excerpt from National Geographic.
In the past month, hundreds of polar bears have strolled past a small town in Canada.
A polar bear watches over two cubs in Hudson Bay, near the town of Churchill, Manitoba. PHOTOGRAPH BY DAVID JENKINS/ROBERT HARDING/CORBIS
It's part of their annual migration back to Hudson Bay, where sea ice is reforming after months of summer melt. To get to the ice each autumn, they traverse Churchill, Manitoba-the "polar bear capital of the world."
These animals are the most studied group of polar bears on Earth. The renowned Ian Stirling, now retired from the Canadian Wildlife Service, began his groundbreaking research here 40 years ago.