The bears are gathering in the Polar Bear Capital of the World. Image: Erinn Hermsen/Polar Bears International

Polar bears ( Ursus maritimus ) are typically solitary creatures. But in a Canadian town on Hudson Bay, the predators gather along the coast every fall to wait for the ice to freeze.

“It’s an incredible phenomenon to experience,” Alysa McCall , director of science at Polar Bears International (PBI), tells Popular Science . “The bears return to this stretch of coast because it’s where the Bay freezes first, thanks to freshwater from the Churchill River plus the Bay’s currents and winds.”

Sea ice platforms help polar bears catch seals, which are their main source of prey.…