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

Steven Kazlowski / Polar bear (Ursus maritimus) adult walking over newly formed pack ice during fall freeze up, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) sow and cub sliding on their backs over the pack ice, much like ice skating, 1002 coastal plain of the Arctic National Wildlife Refuge, Alaska, USA

Steven Kazlowski / Grizzly bear (Ursus arctos horribils) walking on snow, 1002 coastal plain, Arctic National Wildlife Refuge, North Slope of Brooks Range, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) curious cub sits up on its hind legs and tries to balance itself, along Bernard Spit in autumn, 1002 area of the Arctic National Wildlife Refuge, Alaska, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) curious cub sits up on its hind legs, paw raised, and tries to balance itself, along Bernard Spit in autumn, 1002 area of the Arctic National Wildlife Refuge, Alaska, US...

Steven Kazlowski / Polar bear (Ursus maritimus) curious cub stands along Bernard Spit as its mother and other cub rest in the background, 1002 area of the Arctic National Wildlife Refuge, Alaska, USA, October

Ingo Arndt / Caribou (Rangifer tarandus) herd crossing a Kongakut River during summer migration, Arctic National Wildlife Refuge, Alaska

Ingo Arndt / Caribou (Rangifer tarandus) pair crossing a river during summer migration, Arctic National Wildlife Refuge, Alaska

Ingo Arndt / Caribou (Rangifer tarandus) bull crossing a river during summer migration, Arctic National Wildlife Refuge, Alaska

Ingo Arndt / Caribou (Rangifer tarandus) mother and calf crossing a river during summer migration, Arctic National Wildlife Refuge, Alaska

Matthias Breiter / Caribou (Rangifer tarandus) calf running on the tundra, Arctic National Wildlife Refuge, Alaska

Michio Hoshino / Caribou (Rangifer tarandus) herd, Arctic National Wildlife Refuge, Alaska

Michio Hoshino / Caribou (Rangifer tarandus) herd migrating across tundra, Arctic National Wildlife Refuge, Alaska

Michio Hoshino / Caribou (Rangifer tarandus) herd migrating in summer, Arctic National Wildlife Refuge, Alaska

Michio Hoshino / Caribou (Rangifer tarandus) herd migrating across tundra, Arctic National Wildlife Refuge, Alaska

Michio Hoshino / Caribou (Rangifer tarandus) herd stampeding, Arctic National Wildlife Refuge, Alaska

Michio Hoshino / Caribou (Rangifer tarandus) stampeding herd crossing river, Arctic National Wildlife Refuge, Alaska

Michio Hoshino / Caribou (Rangifer tarandus) of the Porcupine Herd climb Brooks Range foothills at midnight during migration, Alaska

Peter Mather / Caribou (Rangifer tarandus) newborn calf nuzzling mother, of the porcupine herd, Arctic National Wildlife Refuge, Alaska

Peter Mather / Caribou (Rangifer tarandus) mother and newborn calf, of the porcupine herd, Arctic National Wildlife Refuge, Alaska

Peter Mather / Caribou (Rangifer tarandus) aerial of the migrating Porcupine herd, crossing river, Arctic National Wildlife Refuge, Alaska

Peter Mather / Caribou (Rangifer tarandus) females and juveniles, from the Porcupine herd, migrating, Arctic National Wildlife Refuge, Alaska

Matthias Breiter / Polar Bear (Ursus maritimus) on coast, Brooks Range, Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) pair of adult sows play with one another on the pack ice during fall freeze up, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) curious spring cub checks out a local elder in snow vehicle outside the arctic village of Kaktovik, Barter Island, 1002 area of the Arctic National Wildlife Refuge, North...

Steven Kazlowski / Polar bear (Ursus maritimus) adult stands on the snow-covered pack ice to get a better look at something in the distance, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) walks through slushy newly forming pack ice at sunrise, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) pair of adults rest and stay cool on the newly formed pack ice in autumn, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) sows with cubs hang out on newly formed pack ice during fall freeze up, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) pair of spring cubs play tug-o-war with a piece of whale remains during freeze up, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) sow on newly formed pack ice with spring cub playing in the water, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) adult resting and staying cool on the newly formed pack ice in autumn, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) sow on newly formed pack ice with spring cub playing in the water, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) female practises breaking a hole in the pack ice, in the 1002 coastal plain of the Arctic National Wildlife Refuge, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) female practises breaking a hole in the pack ice, in the 1002 coastal plain of the Arctic National Wildlife Refuge, Alaska, USA

Steven Kazlowski / White fronted goose (Anser albifrons) adult walking over a frozen freshwater pond, 1002 coastal plain of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Muskox (Ovibos moschantus) profile of a bull on the central arctic coastal plain, North Slope of the Brooks Range, Alaska, USA

Steven Kazlowski / Polar bears (Ursus maritimus) scavenging on baleen whale bones at night in the 1002 coastal plain of the Arctic National Wildlife Refuge, Alaska, USA

Steven Kazlowski / Reindeer (Rangifer tarandus) adult carcass frozen in the snow at -40 below zero, 1002 coastal plain of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Arctic char (Salvelinus alpinus) catch held by silhouetted woman at sunset, 1002 coastal plain of the Arctic National Wildlife Refuge, North Slope, Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) cub plays with a piece of bowhead whale baleen (Balaena mysticetus)along the arctic coast at sunrise, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska...

Steven Kazlowski / Polar bear (Ursus maritimus) 2nd year cub walking along a barrier island in autumn, Bernard Spit, off the 1002 area of the Arctic National Wildlife Refuge, Alaska, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) broken legged sow with pair of spring cubs rest on newly formed pack ice along the arctic coast, 1002 area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, US...

Steven Kazlowski / Polar bear (Ursus maritimus) pair of spring cubs play on newly formed pack ice along the arctic coast in autum, 1002 area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, USA, sequence 2/...

Steven Kazlowski / Polar bear (Ursus maritimus) sow with spring cubs travel across newly formed pack ice during fall freeze up, off the 1002 area of the Arctic National Wildlife Refuge, Alaska, USA, October

Steven Kazlowski / Arctic fox (Alopex lagopus) running profile, its coat changing from summer grey to winter white, 1002 area of the Arctic National Wildlife Refuge, Alaska, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) pair of spring cubs playfully roll around on newly formed pack ice, off the 1002 coastal area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, USA, October

Steven Kazlowski / Photographers shoot a curious Polar bear cub (Ursus maritimus) from a boat off shore from Bernard Spit, Alaska, Beaufort Sea, USA, October 2010

Steven Kazlowski / Polar bear (Ursus maritimus) profile of a 2nd year cub along Bernard Spit, off the 1002 area of the Arctic National Wildlife Refuge, Alaska, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) pair of spring cubs play fighting on newly formed pack ice, off the 1002 coastal area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) pair of sows, one with a spring cub, greet one another on newly formed pack ice along the arctic coast in autumn, 1002 area of the Arctic National Wildlife Refuge, Alaska,...

Steven Kazlowski / Polar bear (Ursus maritimus) spring cub playfully rolls around on newly formed pack ice, off the 1002 coastal area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) spring cub playfully rolls around on newly formed pack ice, off the 1002 coastal area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) pair of spring cubs play on newly formed pack ice along the arctic coast in autum, 1002 area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, USA, sequence 3/...

Steven Kazlowski / Polar bear (Ursus maritimus) sow rolls around on newly formed pack ice along the arctic coast, 1002 Area of the Arctic National Wildlife Refuge, Alaska, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) sow stretches as she gets up from newly formed pack ice along the arctic coast, 1002 area of the Arctic National Wildlife Refuge, Alaska, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) pair of spring cubs play on newly formed pack ice along the arctic coast in autum, 1002 area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, USA, sequence 1/...

Steven Kazlowski / Polar bear (Ursus maritimus) spring cub playfully rolls around on newly formed pack ice, off the 1002 coastal area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) young bear plays with a stick on newly formed pack ice along the arctic coast, 1002 Area of the Arctic National Wildlife Refuge, Alaska, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) broken legged sow with pair of spring cubs rest on newly formed pack ice along the arctic coast, 1002 area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, US...

Steven Kazlowski / Polar bear (Ursus maritimus) sow with two spring cubs travel outside the arctic village of Kaktovik, Bernard Spit, off the 1002 area of the Arctic National Wildlife Refuge, Alaska, USA, October 2010

Steven Kazlowski / Polar bear (Ursus maritimus) spring cub playfully rolls around on newly formed pack ice, off the 1002 coastal area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, USA, October

Steven Kazlowski / Northern lights, Aurora borealis, glow brightly and snake across the night sky, over the Beaufort Sea, off shore from the Arctic National Wildlife Refuge, Alaska, USA, September

Steven Kazlowski / Polar bear (Ursus maritimus) broken legged sow and spring cub rest on newly formed pack ice along the arctic coast in autumn, 1002 area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, US...

Steven Kazlowski / Polar bear (Ursus maritimus) broken legged sow and spring cub rest on newly formed pack ice along the arctic coast in autumn, 1002 area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, US...

Steven Kazlowski / Polar bear (Ursus maritimus) sow and cub along the arctic coast during fall freeze up, off the 1002 area of the Arctic National Wildlife Refuge, Alaska, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) pair of curious spring cubs wade in shallow waters off newly formed pack ice, mother rests behind on ice, Bernard Spit, Alaska, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) curious cub sits up on its hind legs and tries to balance itself, along Bernard Spit in autumn, 1002 area of the Arctic National Wildlife Refuge, Alaska, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) spring cub resting on newly formed pack ice, off the 1002 area of the Arctic National Wildlife Refuge, Alaska, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) spring cub resting on newly formed pack ice, off the 1002 area of the Arctic National Wildlife Refuge, Alaska, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) adult shakes water from its head, 1002 Area of the Arctic National Wildlife Refuge, Alaska, USA, OCtober

Steven Kazlowski / Polar bear (Ursus maritimus) pair of spring cubs sitting next to one another on newly formed pack ice, off the 1002 coastal area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, USA, Octo...

Steven Kazlowski / Polar bear (Ursus maritimus) sow with playful spring cub on newly formed pack ice along the arctic coast in autumn, 1002 area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) profile of a spring cub on newly formed pack ice, off Barter Island and the 1002 area of the Arctic National Wildlife Refuge, Alaska, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) sow rolls around and stretches on newly formed pack ice along the arctic coast, 1002 area of the Arctic National Wildlife Refuge, Alaska, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) spring cub playfully rolls around on newly formed pack ice, off the 1002 coastal area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) pair of spring cubs play on newly formed pack ice along the 1002 coastal area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea, USA, October

Steven Kazlowski / Polar bear (Ursus maritimus) 3 year old sits along Bernard Spit as it waits for the freeze up, Arctic National Wildlife Refuge, Alaska, USA, September

Steven Kazlowski / Polar bear (Ursus maritimus) profile of a 3 year old along Bernard Spit, Arctic National Wildlife Refuge, Alaska, USA, September

Steven Kazlowski / Polar bear (Ursus maritimus) 3 year old sits along Bernard Spit as it waits for the freeze up, Arctic National Wildlife Refuge, Alaska, USA, September

Steven Kazlowski / Polar bear (Ursus maritimus) curious 3 year old stands up on Bernard Spit as it waits for the freeze up, Arctic National Wildlife Refuge, Alaska, USA, September

Steven Kazlowski / Arctic fox (Alopex lagopus) sits upon and feeds on a Bowhead whale (Balaena mysticetus) jawbone, Barter Island, Alaska, USA, November

Ingo Arndt / Caribou (Rangifer tarandus) herd crossing a river during summer migration, Arctic National Wildlife Refuge, Alaska

Ingo Arndt / Caribou (Rangifer tarandus) herd crossing a river during summer migration, Arctic National Wildlife Refuge, Alaska

Ingo Arndt / Caribou (Rangifer tarandus) herd during summer migration, Arctic National Wildlife Refuge, Alaska

Ingo Arndt / River channels, Brooks Range, Arctic National Wildlife Refuge, Alaska

Ingo Arndt / Hills beside Kongakut River in late light, Arctic National Wildlife Refuge, Alaska

Ingo Arndt / Cumulus clouds in blue sky over hills, Kongakut River, Arctic National Wildlife Refuge, Alaska

Ingo Arndt / Caribou (Rangifer tarandus) bull crossing a river during summer migration, Arctic National Wildlife Refuge, Alaska

Ingo Arndt / Caribou (Rangifer tarandus) bull, Arctic National Wildlife Refuge, Alaska