Paul Hobson / Brown bear (Ursus arctos) adult female with two cubs playing, Finland, June

Paul Hobson / Brown bear (Ursus arctos) two fighting, Finland, June

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

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

Nature Production / Asiatic black bear (Ursus thibetanus) cub climbing tree, Russia, spring

Axel Gomille / Sloth Bear (Melursus ursinus) mother with cub riding on her back. Karnataka, India, April.

Axel Gomille / Sloth Bear (Melursus ursinus) female with large cubs (on right) trying to fight off rogue male. Karnataka, India, March.

Axel Gomille / Sloth Bear (Melursus ursinus) mother and cubs with one riding on her back. Karnataka, India, March.

Axel Gomille / Sloth Bear (Melursus ursinus) climbing on tree. Karnataka, India, March.

Axel Gomille / Sloth Bear (Melursus ursinus) cub playing with with mother's paw. Karnataka, India, March.

Axel Gomille / Portrait of a young adult male Sloth Bear (Melursus ursinus) standing on hind legs by a rock. Karnataka, India, March.

Axel Gomille / Sloth Bear (Melursus ursinus) mother with cub riding on her back. Karnataka, India, April. Did you know? The sloth bear is the only bear that carries its young on its back.

Axel Gomille / Portrait of a young adult male Sloth Bear (Melursus ursinus). Karnataka, India, March.

Lassi Rautiainen / Brown bear (Ursus arctos) in woodland wetlands, Kuhmo, Finland, September 2010

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

Lassi Rautiainen / Brown bear (Ursus arctos) and Grey wolf (Canis lupus) showing aggression, Kuhmo, Finland, September

Lassi Rautiainen / Two Brown bears (Ursus arctos) fighting in woodland wetlands, Kuhmo, Finland, July

Eric Baccega / Polar Bear (Ursus maritimus) mother with her 3-month cub, soon after emerging from their hibernation den. Wapusk National Park, Manitoba, Canada, March.

Eric Baccega / Polar Bear (Ursus maritimus) mother resting while her 3-month cubs play. Wapusk National Park, Manitoba, Canada, March.

Diane McAllister / Coastal Brown bear (Ursus arctos) female standing up and looking around while eating sedge grass in Lake Clark National Park. Alaska, USA, July

Diane McAllister / Brown bear (Ursus arctos) strolling along the beach in the rain, looking towards the camera. Lake Clark National Park, Alaska, USA, July

Diane McAllister / Coastal Brown bear (Ursus arctos horribilis) female and her cub standing in the long grass. She is looking warily at an approaching boar. Lake Clark National Park, Alaska, USA, July

Eric Baccega / Polar Bear (Ursus maritimus) walking on icepack with arctic coast in the background. Floe edge, Arctic Bay, Baffin Island, Nunavut, Canada, April.

Matthew Maran / Black Bear (Ursus americanus) with a Chinook Salmon (Oncorhynchus tshawytscha) in its mouth. Ucluth Inlet, Barkley Sound, Vancouver Island, Canada, September.

Matthew Maran / Black Bear (Ursus americanus) with a Chinook Salmon (Oncorhynchus tshawytscha) in its mouth. West coast of Vancouver Island, Canada, October.

Andy Rouse / Polar Bear (Ursus maritimus) mother and two cubs playing around iceberg. Svalbard, Norway, Europe, February.

Andy Rouse / close up portrait of a Polar Bear (Ursus maritimus), about three year. Svalbard, Norway, Europe, February.

Andy Rouse / Polar Bear (Ursus maritimus) large male on pack ice. Svalbard, Norway, Europe, February.

Andy Rouse / Polar Bear (Ursus maritimus) mother standing on hind legs, and cub (18 months old). Svalbard, Norway, Europe, February.

Andy Rouse / Two Polar Bears (Ursus maritimus) swimming. Svalbard, Norway, Europe, February.

Andy Rouse / Two Polar Bear (Ursus maritimus) new year cubs (6 months). Svalbard, Norway, Europe, February.

Andy Rouse / Silhouetted Grizzly Bear (Ursus arctos horribilis) walking. Katmai, Alaska, USA, September.

Andy Rouse / Grizzly Bear (Ursus arctos horribilis) peering into a remote camera. Katmai, Alaska, USA, September.

Andy Rouse / Grizzly Bear (Ursus arctos horribilis) chasing gulls away from his salmon hunting territory. Katmai, Alaska, USA, September.

Andy Rouse / Solitary Grizzly Bear (Ursus arctos horribilis) in expansive mountain landscape. Katmai, Alaska, USA, August.

Andy Rouse / Grizzly Bear (Ursus arctos horribilis) walking through a river with caught salmon against a mountainous landscape as two gulls fly past. Katmai, Alaska, USA, August.

Andy Rouse / Grizzly Bear (Ursus arctos horribilis) with caught salmon, another bear more distant, with mountains backing the scene. Katmai, Alaska, USA, August.

Andy Rouse / Grizzly Bear (Ursus arctos horribilis) mother with two young cubs. Katmai, Alaska, USA, August.

Andy Rouse / Grizzly Bear (Ursus arctos horribilis) thrashing a large caught salmon. Katmai, Alaska, USA, August.

Andy Rouse / Grizzly Bear (Ursus arctos horribilis) with a large salmon in its mouth. Katmai, Alaska, USA, August.

Andy Rouse / Grizzly Bear (Ursus arctos horribilis) running through water after salmon. Katmai, Alaska, USA, August.

Andy Rouse / Grizzly Bear (Ursus arctos horribilis) running through water after salmon. Katmai, Alaska, USA, August.

Andy Rouse / Grizzly Bear (Ursus arctos horribilis) chasing through water after salmon. Katmai, Alaska, USA, August.

Andy Rouse / Grizzly Bear (Ursus arctos horribilis) male (right) and female fighting in water over salmon. Katmai, Alaska, USA, August.

Andy Rouse / Grizzly Bear (Ursus arctos horribilis) male (right) and female fighting in water over salmon. Katmai, Alaska, USA, August.

Andy Rouse / Grizzly Bear (Ursus arctos horribilis) with caught salmon. Katmai, Alaska, USA, August.

Andy Rouse / Grizzly Bear (Ursus arctos horribilis) walking through water with caught salmon in its mouth. Katmai, Alaska, USA, August.

Andy Rouse / Grizzly Bear (Ursus arctos horribilis) standing on hind legs in water with caught salmon. Katmai, Alaska, USA, August.

Andy Rouse / Grizzly Bear (Ursus arctos) on the move in late evening light after heavy rain. Alaska, USA, June.

Peter Cairns / Young female European Brown Bear (Ursus arctos) in woodland. Martinselkonen, Suomassalmi, Finland, June.

Chris Shields / Illustration of wildlife of the Andes: South America Alpaca (Vicugna pacos),centre; Cougar / Puma / Mountain lion / Mountain cat / Catamount / Panther (Puma concolor),left; Spectacled / Andean bear (...

Sergey Gorshkov / Kamchatka Brown bear (Ursus arctos beringianus) leaping through water to catch salmon in river, Kamchatka, Far east Russia, August

Sergey Gorshkov / Kamchatka Brown bear (Ursus arctos beringianus) walking beside lake, Kamchatka, Far east Russia, August

Sergey Gorshkov / Kamchatka brown bear (Ursus arctos beringianus) mating, Kamchatka, Far east Russia, May

Sergey Gorshkov / Kamchatka Brown bear (Ursus arctos beringianus) walking beside lake, Kamchatka, Far east Russia, August

Sergey Gorshkov / Kamchatka brown bear (Ursus arctos beringianus) mother and three cubs swimming across lake, Kamchatka, Far east Russia, June

Sergey Gorshkov / Kamchatka Brown bear (Ursus arctos beringianus) catching salmon in river, Kamchatka, Far east Russia, August

Sergey Gorshkov / Kamchatka Brown bear (Ursus arctos beringianus) catching migration salmon in river, Kamchatka, Far east Russia, August

Sergey Gorshkov / Kamchatka Brown bears (Ursus arctos beringianus) fighting, Kamchatka, Far east Russia, July

Sergey Gorshkov / Kamchatka Brown bear (Ursus arctos beringianus) running through water, fishing, Kamchatka, Far east Russia, August

Sergey Gorshkov / Kamchatka brown bear (Ursus arctos beringianus) mother leads three cubs over hillside in snow, Kamchatka, Far east Russia, May

Sergey Gorshkov / Silhouette of Kamchatka Brown bear (Ursus arctos beringianus) ) beside Lake Kuril at dawn, Kamchatka, Far east Russia, August 2008

Shattil & Rozinski / Kelp floating on water at the edge of the Great Bear Rainforest, British Columbia, Canada, September

Matthias Breiter / Kermode Bear (Ursus americanus kermodei), white morph called spirit bear, northern British Columbia, Canada

Eric Baccega / Grizzly bear (Ursus arctos horribilis) mother and four spring cubs, walking along dirt track, Katmai National Park, Alaska, USA, July

Kevin Schafer / Polar bear (Ursus maritimus) resting on pack ice, Svalbard, Arctic Norway, vulnerable species 2010

Kevin Schafer / Polar bear (Ursus maritimus) sitting on pack ice, Svalbard, Arctic Norway, vulnerable species 2010

Angelo Gandolfi / Brown Bear (Ursus arctos) climbing tree, South Carpathian mountains, Romania

Angelo Gandolfi / Brown Bear (Ursus arctos) Abruzzo National Park, Italy, December

Angelo Gandolfi / Brown Bear (Ursus arctos) cubs, with paws leaning on car window, South Carpathian mountains, Romania

Bryan and Cherry Alexander / Tourists on icebreaker "Professor Multanovskiy" watching Polar bear (Ursus maritimus) in pack ice. Svalbard, Norway, 2004.

Edwin Giesbers / Malayan Sun Bear (Ursus malayanus) head portrait. Captive-native to southeast Asia. Vulnerable

Laurent Geslin / Brown bear (Ursus arctos) climbing over wall to reach rubbish bins. Brasov, Romania.

Eric Baccega / Polar bear (Ursus maritimus) female and her two cubs on large iceberg off Baffin Island. Nunavut, Canada, August 2010

Eric Baccega / Polar bear (Ursus maritimus) female and her two cubs on large iceberg off Baffin Island. Nunavut, Canada, August 2010

Eric Baccega / Polar bear (Ursus maritimus) female and her two cubs on an iceberg, off Baffin Island. Nunavut, Canada, August 2010

Steven Kazlowski / Polar bear (Ursus maritimus) female with cubs aged two years, along a barrier island during fall freeze up, Barter Island, 1002 area of the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bears (Ursus maritimus) female with cubs aged two years travelling along a barrier island during autumn freeze up, Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Photographers photographing of a group of curious Polar bears (Ursus maritimus) from motorboats along a barrier island during autumn freeze up, Barter Island, 1002 area of the Arctic National Wildlife...

Steven Kazlowski / Polar bear (Ursus maritimus) young male playing / rolling around in the snow along a barrier island during autumn freeze up, Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) portrait of curious young male, covered in snow from rolling around / playing. On a barrier island during autumn freeze up, Bernard Spit, 1002 area of the Arctic National...

Steven Kazlowski / Polar bear (Ursus maritimus) young boar playing / rolling around in the snow along a barrier island during autumn freeze up, Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Two Polar bear (Ursus maritimus) newborn cubs playing outside their den, mouth of Canning River along the Arctic coast, eastern Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) sow with newborn spring cub newly emerged from their den, mouth of Canning River along the Arctic coast, eastern Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) head portrait of adult scenting the wind, Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) juvenile shaking off snow after rolling around on the pack ice, arctic coast, 1002 area of the Arctic National Wildlife Refuge, Alaska, Beaufort Sea

Steven Kazlowski / Polar bear (Ursus maritimus) profile portrait of juvenile, Bernard Spit, Arctic National Wildlife Refuge, Alaska

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) footprints in the snow along a barrier island during autumn freeze up, Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, Alaska. October 2009

Steven Kazlowski / Polar bear (Ursus maritimus) portrait of a juvenile male playing in the slushy freezing water, Bernard Spit, 1002 area of the Arctic National Wildlife Refuge, Alaska.

Donald M. Jones / Black Bear (Ursus americanus) yearling cub at base of spruce tree, Alberta, Canada

Donald M. Jones / Black Bear (Ursus americanus) yearling cub up in a Lodgepole Pine (Larix laricina), Alberta, Canada

Edwin Giesbers / Asiatic black / Moon bear (Ursus thibetanus) aggressive behaviour displayed between two individuals, captive; Isselburg zoo; Germany.

Edwin Giesbers / Two Kodiak / Alaskan brown bears (Ursus arctos middendorffi) close up, fighting, captive.

Edwin Giesbers / European Brown Bear (Ursus arctos) head portrait, with mouth open, captive.

Edwin Giesbers / European Brown Bear (Ursus arctos) head portrait, with mouth open, captive.