Steven Kazlowski,Steven Kazlowski / Polar bear (Ursus maritimus) juvenile spreading body weight over thin newly forming pack ice, trying not to break through, Beaufort Sea, off the 1002 area of the Arctic National Wildlife Refuge, North...

Steven Kazlowski,Steven Kazlowski / Polar bear (Ursus maritimus) juvenile rolling around on newly formed pack ice, Beaufort Sea, off the 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska

Steven Kazlowski,Steven Kazlowski / Polar bear (Ursus maritimus) portrait, female. Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska.

Steven Kazlowski,Steven Kazlowski / Polar bear (Ursus maritimus) curious adult head underwater, Beaufort Sea, off the 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska.

Steven Kazlowski,Steven Kazlowski / Polar bear (Ursus maritimus) young bear in freezing water during autumn freeze up, Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, Beaufort Sea

Steven Kazlowski,Steven Kazlowski / Polar bear (Ursus maritimus) 4-5 year-old on pack ice, low angle shot, off the 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, Beaufort Sea, autumn

Nick Garbutt / Polar bear (Ursus maritimus) grazing out side the perimeter fence at Nanuk Lodge, shores of Hudson Bay, Canada, being filmed by cameraman, John Aitchison, for the BBC NHU for series "Frozen Planet", S...

Nick Garbutt / Polar bear (Ursus maritimus) being filmed by BBC NHU for series "Frozen Planet" with producer Miles Barton and cameraman Adam Ravetch, near Nanuk Lodge, shores of Hudson Bay, Manitoba, Canada, late Se...