The polar bear is an evolutionary freak. He is white, web-footed, and loves to swim. In icy waters! Go figure. But the strangest twist to the polar bear story is not about color or locomotion, but rather biorhythm reversal. This is well studied in a southern population that lives near Churchill, Manitoba, on the shores of Hudson Bay. To master the world of the ringed seal, its main prey in this part of the world, these bruins have executed a biological about face. They're awake in winter and mostly sleep in summer. How's that for bassackwards?

After Hudson Bay freezes in November these bears, instead of going to sleep like grizzlies and blacks, amble onto the ice, head south, and begin to hunt for seals through the long Arctic night. They look for breathing holes belonging to a male seal, then crouch and lie in wait, sometimes for hours, sometimes for days. When an unsuspecting seal pokes his head out to take a breath, the bear swipes and the blubbery pinniped goes flying through the air like a rag doll. Voila! Polar bear bacon.

In summertime the ice is gone so seals can frolic and fish at their leisure, unconcerned about bears and breathing holes. The polar bears, on the other hand, mope around and amble slowly northward, half asleep and full of hunger and grump. Their destination is Churchill, which they reach in several months, and where they hang out and await the precious freeze-up, so they can once again hunt seals.