Igor Shpilenok / Kamchatka Brown bear (Ursus arctos beringianus) standing whilst fishing for Salmon in Tikhaya / 'Calm' River with Kronotsky volcano, Kamchatka, Kronotsky Zapovednik Reserve, Russia.

Igor Shpilenok / Kamchatka brown bear (Ursus arctos beringianus) mother and cub on tundra, Kronotsky Zapovednik Reserve, Kamchatka, Russia.

Eric Baccega / Spectacled bear {Tremarctos ornatus} 3-month cub, captive. occurs South America

Eric Baccega / Female Spectacled bear {Tremarctos ornatus} head portrait amongst vegetation, captive. occurs South America

Suzi Eszterhas / Polar Bear {Ursus maritimus} 3/4-months cubs peeking over mother who has been anaesthetised by biologists, Wapusk NP, Manitoba, Canada

George McCarthy / Black Bear {Ursus americanus} portrait, Alaska, USA

George McCarthy / Black Bear (Ursus americanus) Grand Teton National Park, Wyoming, USA

Matthew Maran / Black bear (Ursus americanus) scratching its head. Clayoquot Sound, Vancouver Island, Canada

Igor Shpilenok / Kamchatka brown bear (Ursus arctos beringianus) enjoys hot steam from a geyser in Valley of the Geysers, Kronotsky Zapovednik, Kamchatka, Far East Russia

Eric Baccega / Head portrait of a Giant panda (Ailuropoda Melanoleuca) Bifengxia Giant Panda Breeding and Conservation Center, Yaan, Sichuan, China

Eric Baccega / Head portrait of a Giant panda (Ailuropoda Melanoleuca) Bifengxia Giant Panda Breeding and Conservation Center, Yaan, Sichuan, China

Steven Kazlowski / Polar bear (Ursus maritimus) juvenile, 1002 area of the Arctic National Wildlife Refuge, Alaska

Matthew Maran / Black Bear (Ursus americanus) at waters edge, Barkley Sound, Vancouver Island, British Columbia, Canada

Eric Baccega / Grizzly bear (Ursus arctos horribilis) catching salmon in Brooks river, Katmai National Park, Alaska, USA, July

Peter Cairns / naturepl.com / European brown bear (Ursus arctos) with three cubs, Finland, June

George Sanker / Young Black bear (Ursus americanus) cub climbing mature fir tree, Yellowstone National Park, Wyoming, USA, May

George Sanker / Grizzly Bear (Ursus arctos horribilis) in sage brush above meadow and trees. Grand Teton National Park, June.

Steven Kazlowski / Polar bear (Ursus maritimus) sow with her cub outside their den in late winter, Arctic coast of Alaska, USA

Steven Kazlowski / Polar bear (Ursus maritimus) sow standing with her cub outside their den in late winter, Arctic coast of Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) traveling along the coast on sea ice in search of seals, Svalbard, Norway

Steven Kazlowski / Polar bear (Ursus maritimus) head close-up portrait of an adult male, with snowflakes on fur, Barter Island, 1002 area of the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) sow hunting for seals amidst the sea ice floating off the coast of Svalbard, Arctic.

Steven Kazlowski / Polar bear (Ursus maritimus) portrait of a tagged and collared female in early autumn, with snow on her face. Barter Island, 1002 area of the Arctic National Wildlife Refuge, Alaska

Orsolya Haarberg / Brown bear (Ursus arctos) in woodland, Finland.

Diane McAllister / Coastal Brown Bear (Ursus arctos horribilis) female and her cub sit upright briefly as if posing. Lake Clark National Park Alaska, USA, July.

Lassi Rautiainen / Brown bear (Ursus arctos) wallowing in mud in woodland wetlands, Kuhmo, Finland, July

Lassi Rautiainen / Brown bear (Ursus arctos) and Grey wolf (Canis lupus) together in wetlands, Kuhmo, Finland, July

Wild Wonders of Europe / Lesniewski / Wild Brown Bear (Ursus arctos) in mountain meadow. Bieszczady, Carpathian Mountains, Poland, May.

Paul Hobson / Brown bear (Ursus arctos) two grazing beside water, Finland, June

George Sanker / Grizzly Bear (Ursus arctos horribilis) mother with three young cubs. Grand Teton National Park, Wyoming, USA, June.

Gerrit Vyn / Black bear (Ursus americana) foraging for alpine berries during Autumn, Cascade Mountains, Washington, USA

George Sanker / Grizzly bear (Ursus arctos horribilis) walking through long grass, Yellowstone NP, Wyoming, USA, October

Danny Green / Brown Bear (Ursus arctos) and cub. Finland, Europe, June.

Danny Green / Brown Bear (Ursus arctos) and cubs in meadow. Finland, Europe, June.

Danny Green / Brown Bear (Ursus arctos) by water, reflected. Finland, Europe, June.

Danny Green / Brown Bear Cubs (Ursus arctos) play fighting. Finland, Europe, June.

Steven Kazlowski / Two curious young Polar bears (Ursus maritimus), Barter Island, off the 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, October 2011

Steven Kazlowski / Young Polar bear (Ursus maritimus) standing and trying to balance in shallow water along the Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, North Slope of the Brooks Range, Alaska, Oc...

George Sanker / Black bear (Ursus americanus) young cub portrait, Yellowstone National Park, Wyoming, USA

Loic Poidevin / Grizzly bear (Ursus arctos horribilis) salmon fishing in river rapids, Katmai National Park, Alaska, USA

Steven Kazlowski / Grizzly bear (Ursus arctos horribils) sow sits in riverbed with a mountain range in background, east coast of Katmai National Park on the Alaskan peninsula, USA

Steven Kazlowski / Polar bear (Ursus maritimus) underwater view swimming in a pool, Anchorage Zoo, Alaska, USA. No release available.

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

Danny Green / Brown Bear (Ursus arctos) cub climbing up a tree. Finland, July.

Danny Green / Brown Bear (Ursus arctos) cubs, three standing in a line on their hind legs. Finland, July.

Danny Green / Brown Bear (Ursus arctos) female with three young cubs on meadow. Suomussalmi, Kainuu Region, Finland, July.

Todd Mintz / Grizzly Bear (Ursus arctos horribillis) and cub in water, play fighting. Great Bear Rainforest, British Columbia, Canada, September.

George Sanker / American Black Bear (Ursus americanus) cub. Yellowstone National Park, Wyoming, June.

George Sanker / Grizzly Bear (Ursus arctos horribilis) mother and cubs. Grand Teton National Park, Wyoming, USA, June.

Loic Poidevin / Polar bear (Ursus maritimus) female with cubs, Wapusk National park Manitoba, Canada, March

Igor Shpilenok,Igor Shpilenok / Kamchatka Brown Bear (Ursus arctos beringianus) stands on its back legs to more easily determine the source of an unfamiliar sound. Kronotsky Zapovednik Nature Reserve, Kamchatka Peninsula, Russian Fa...

Eric Baccega / Polar bear (Ursus maritimus) mother resting with one 3 month cub, coming out of den, March. Wapusk National Park, Manitoba, Canada, February.

Steven Kazlowski / Polar bear (Ursus maritimus) curious young bear along Bernard Spit, a barrier island, during autumn freeze up, 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) curious young male on the newly frozen pack ice, Beaufort Sea, off the 1002 area of the Arctic National Wildlife Refuge, North Slope, Alaska

George Sanker / Cinnamon bear, subspecies of black bear (Ursus americanus cinnamomum) cub in tree. Yellowstone National Park, Wyoming, USA, May.

George Sanker / Cinnamon bear, subspecies of black bear (Ursus americanus cinnamomum) cub in tree. Yellowstone National Park, Wyoming, USA, May.

Juan Carlos Munoz / European brown bear (Ursus arctos) on rock ledge, captive, Cabarceno Park, Cantabria, Spain, June.

Juan Carlos Munoz / Brown bear (Ursus arctos) silhouetted at dawn, Karelia. Finland, May.

Jussi Murtosaari / European brown bear (Ursus arctos arctos) scratching its back, northern Finland, June.

Charlie Summers / Brown Bear (Ursus arctos) swimming in the Anan Creek Lagoon of Alaska, July.

Charlie Summers / Black Bear (Ursus americanus) with Pink Salmon (Oncorhynchus gorbuscha) catch, Anan Creek, Alaska, July.

Eric Baccega / Polar bear (Ursus maritimus) female coming out the den with one three month cub. Wapusk National Park, Churchill, Manitoba, Canada, March.

Eric Baccega / Polar bear cub 3 months (Ursus maritimus) playing in the front of the day den in march. Wapusk National Park. Churchill, Manitoba, Canada