A polar bear (Ursus maritimus) on the tundra near Churchill, Hudson Bay, far north Manitoba, Canada. During a six-week span in October and November this area has the highest concentration of polar bears in the world. The bears assemble along the coast, and wait for the sea ice to form so they can begin hunting seals. The bears fast during this time, so if the ice forms later in the year, the bears must fast for longer, therefore decreasing their chances of surviving until winter.  As global temperatures warm, the bears in this area are struggling to adapt in time to meet the longer summers. This is demonstrated in many ways, including the number of cubs a female has each season. Fifteen years ago it was common to see a mother bear with three babies, and seven years ago twins were still common. Now bears here seldom give birth to more than one cub, and many females are not fit enough to produce even a single offspring.  Photo © William Drumm, 2013.
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