Jim Brandenburg / Arctic Wolf (Canis lupus) male sitting on iceberg, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Arctic Wolf (Canis lupus) with begging pup, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Polar Bear (Ursus maritimus) running across ice, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Polar Bear (Ursus maritimus) running over icefield during spring thaw, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Polar Bear (Ursus maritimus) walking on ice floe, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Arctic Hare (Lepus arcticus) group gathering in summer, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Arctic Hare (Lepus arcticus) camouflaged on snow, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Muskox (Ovibos moschatus) on snowy rocks, Ellesmere Island, Nunavut, Canada

Flip Nicklin / Polar Bear (Ursus maritimus) cub searching underwater for mother who is hunting, Baffin Island, Nunavut, Canada

Flip Nicklin / Sea anemones, Admiralty Inlet, Lancaster Sound, Nunavut, Canada

Flip Nicklin / Sea Star, Anemones and Coralline Algae living 40 feet below the water surface, Admiralty Inlet, Lancaster Sound, Nunavut, Canada

Flip Nicklin / Brittle Star, Admiralty Inlet, Baffin Island, Canada

Flip Nicklin / Jellyfish, Admiralty Inlet, Lancaster Sound, Nunavut, Canada

Flip Nicklin / Polar Bear (Ursus maritimus) swimming, Baffin Island, Nunavut, Canada

Flip Nicklin / Polar Bear (Ursus maritimus) shakes, off water, Wager Bay, Canada

Jim Brandenburg / Arctic Fox (Alopex lagopus) portrait, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Arctic Wolf (Canis lupus) portrait, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Arctic Wolf (Canis lupus) howling, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Arctic Wolf (Canis lupus) in blizzard, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Arctic Wolf (Canis lupus) pup howling, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Peary Caribou (Rangifer tarandus pearyi) running, Ellesmere Island, Nunavut, Canada

Flip Nicklin / Bowhead Whale (Balaena mysticetus) tail, Baffin Island, Nunavut, Canada

Jim Brandenburg / Arctic Wolf (Canis lupus) pup howling, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Arctic Wolf (Canis lupus) pups, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Arctic Wolf (Canis lupus) pup begging for food from parent, Ellesmere Island, Nunavut, Canada

Flip Nicklin / Polar Bear (Ursus maritimus) swimming, Wager Bay, Canada

Flip Nicklin / Atlantic Walrus (Odobenus rosmarus rosmarus), Baffin Island, Nunavut, Canada

Flip Nicklin / Bowhead Whale (Balaena mysticetus) noses the kayak of biologist Kerry Finley, Isabella Bay, Baffin Island, Canada

Flip Nicklin / Beluga (Delphinapterus leucas) whale, group swimming along ice edge, Lancaster Sound, Nunavut, Canada

Flip Nicklin / Beluga (Delphinapterus leucas) whale portrait at 200 feet underwater, Lancaster Sound, Nunavut, Canada

Flip Nicklin / Narwhal (Monodon monoceros) surfacing, Baffin Island, Nunavut, Canada

Flip Nicklin / Narwhal (Monodon monoceros) males sparring over carcass of dead female, Baffin Island, Canada

Flip Nicklin / Narwhal (Monodon monoceros) group in ice break, Baffin Island, Nunavut, Canada

Flip Nicklin / Narwhal (Monodon monoceros) group of males, Baffin Island, Nunavut, Canada

Flip Nicklin / Narwhal (Monodon monoceros) males, Lancaster Sound, Baffin Island, Canada

Jim Brandenburg / Iceberg, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Arctic Wolf (Canis lupus) pup howling, Ellesmere Island, Nunavut, Canada

Flip Nicklin / Beluga (Delphinapterus leucas) pod swimming and molting in freshwater shallows, Somerset Island, Nunavut, Canada

Jim Brandenburg / Arctic Wolf (Canis lupus) leaping onto ice floe, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Arctic Wolf (Canis lupus) walking into wind, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Muskox (Ovibos moschatus) herd in defensive formation, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Arctic Hare (Lepus arcticus) babies camouflaged on tundra, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Arctic Wolf (Canis lupus) trio at sunset, Ellesmere Island, Nunavut, Canada

Jim Brandenburg / Arctic Wolf (Canis lupus) pups at den entrance, Ellesmere Island, Nunavut, Canada

Flip Nicklin / Polar Bear (Ursus maritimus) swimming, Wager Bay, Canada

Flip Nicklin / Polar Bear (Ursus maritimus) swimming, Baffin Island, Nunavut, Canada

Toby Sinclair / People impersonating Langur monkeys at fruit stall. New Delhi, India, street theatre

Michael Pitts / Saltwater crocodile hatchling on adult's head {Crocodylus porosus} NT, Australia

Michael Pitts / Mertens water monitor swimming {Varanus mertensi} Litchfield NP Australia

Pete Oxford / Emperor penguins, Antarctica. (Aptenodytes forsteri) Australian antarctic territory

Pete Oxford / Edge of fast ice with Adelie penguins, Australian Antarctic Territory, Antarctica

David Noton / Panoramic view of Ayer's rock (Uluru) Northern Territories, Australia

Pete Oxford / Emperor penguin and chick, Australian Antarctic Territory, Antarctica.

Pete Oxford / Emperor penguins walking. Australian Antarctic Territory, Antarctica

Pete Oxford / Emperor penguin colony chicks and adults, Australian Antarctic territory

Tony Heald / Little corella perched {Cactua sanguinea} Northern Territory, Australia

Tony Heald / 'Cool burn' fire, canopy is unaffected, Kakadu NP, Northern Territory, Australia

Steven David Miller / Perentie {Varanus giganteus} Northern Territory, Australia, Alice Springs Reptile Park - largest Australian monitor lizard

Pete Oxford / Iceberg, Auster 'EP' rookery, Australian Antarctic Territory, Antarctica

Pete Oxford / Emperor penguin walking over ice at sunset, Australian Antarctic Territory, Auster rookery

Gavin Hellier / People leaving the Jama Masjid, Friday Mosque, after the Friday Prayers, Old Delhi, Delhi, India 2011

Jeff Vanuga / Kirk's Dikdik (Madoqua kirki) marking territory by defecating, Samburu National Reserve, Kenya, Africa.

Neil Aldridge / Portrait of a meerkat (Suricata suricatta) or suricate, looking at the camera and standing to survey its territory on the edge of Makgadikgadi Pans National Park, Botswana, April.

Neil Aldridge / Side-on portrait of a Meerkat (Suricata suricatta) standing to survey its territory near the edge of Botswana's Makgadikgadi Pans National Park in the Kalahari. April.

Neil Aldridge / Meerkat (Suricata suricatta) standing to survey its territory on the edge of Makgadikgadi Pans National Park, Botswana, April.

Neil Aldridge / Meerkat (Suricata suricatta) standing to survey its territory on the edge of Makgadikgadi Pans National Park, Botswana, April.

Neil Aldridge / Meerkat (Suricata suricatta) looking at the camera and standing to survey its territory on the edge of Makgadikgadi Pans National Park, Botswana, April.

Neil Aldridge / Meerkat (Suricata suricatta) standing in alert pose to survey its territory on the edge of Makgadikgadi Pans National Park, Botswana, April.

Neil Aldridge / Two meerkats (Suricata suricatta) or suricates, standing in alert pose surverying their territory on the edge of Makgadikgadi Pans National Park, Botswana, April.

Neil Aldridge / Alarmed by the presence of a predator, a group of meerkats (Suricata suricatta) or suricates, stand together on high ground to survey their territory on the edge of Makgadikgadi Pans National Park, Bo...

Neil Aldridge / Meerkat (Suricata suricatta) standing in alert pose to survey its territory on the edge of Makgadikgadi Pans National Park, Botswana, April.

Neil Aldridge / Meerkat (Suricata suricatta) standing in alert pose to survey its territory on the edge of Makgadikgadi Pans National Park, Botswana, April.

Neil Aldridge / Meerkat (Suricata suricatta) standing to survey its territory on the edge of Makgadikgadi Pans National Park, Botswana, April.

Neil Aldridge / Meerkat (Suricata suricatta) standing to survey its territory on the edge of Makgadikgadi Pans National Park, Botswana, April.

Neil Aldridge / Meerkat (Suricata suricatta) standing in alert pose to survey its territory on the edge of Makgadikgadi Pans National Park, Botswana, April.

Paul Hobson / Avocet (Recurvirostra avosetta) two pairs fighting over territory, Texel, Holland May

Paul Hobson / Avocet (Recurvirostra avosetta), two pairs disputing territory, Texel, Holland May

Matthew Maran / Raccoon (Procyon lotor) climbing out of a lake, escaping the nipping beak of a swan, defending its territory, Stanley Park, Vancouver, BC, Canada

Neil Aldridge / An elderly Zu/'hoasi Bushman carrying a spear, bow and quiver of arrows on the plains of the Kalahari, Botswana. April 2012.

Ingo Arndt / Leichhardt's Grasshopper (Petasida ephippigera) on Pityrodia (Pityrodia jamesii) plant, Kakadu National Park, Northern Territory, Australia

Ingo Arndt / Leichhardt's Grasshopper (Petasida ephippigera) on Pityrodia (Pityrodia jamesii) plant, Kakadu National Park, Northern Territory, Australia

Michael Quinton / Dall's Sheep (Ovis dalli) ram injured in fight over a female, Yukon, Canada

Michael Quinton / Dall's Sheep (Ovis dalli) ram, Yukon, Canada

Christophe Courteau / Cheetah (Acinonyx jubatus) male marking territory on tree in the Kalahari Desert, Botswana

Christophe Courteau / African wild dog marking territory Okavango delta Botswana {Lycaon pictus}

Oriol Alamany / Male African lion (Panthera leo) marking his territory at night, Kruger National Park, Transvaal, South Africa, September.

Steven David Miller / Striated green heron (Butorides striatus) on mangrove tree branch, Yellow Waters wetland, South Alligator River, Kakadu National Park, Northern Territory, Australia

Steven David Miller / Rose crowned fruit dove (Ptilinopus regina) resting on branch, Northern Territory Wildlife Park, Darwin, Australia, captive

Steven David Miller / Little Corella (Cacatua sanguinea) pair perched in tree together, Mary River, Northern Territory, Australia

Steven David Miller / Little Corella (Cacatua sanguinea) pair preening, Mary River, Northern Territory, Australia

Steven David Miller / Great grey bowerbird (Chlamydera nuchalis) bower of a male bird showing the bird's attraction to white objects which it uses to decorate the 'runway' of the bower, Berry Springs, Northern Territory,...

Steven David Miller / Australian Freshwater crocodile (Crocodylus johnstoni) Tumbling Waters Caravan Park, Northern Territory, Australia

Steven David Miller / Australian Freshwater crocodile (Crocodylus johnstoni) raising body temperature in sun, sometimes it will open mouth to cool off, Tumbling Waters Caravan Park, Northern Territory, Australia

Steven David Miller / Australian Freshwater crocodile (Crocodylus johnstoni) raising body temperature in sun, Mary River, Northern Territory, Australia

Steven David Miller / Saltwater crocodile (Crocodylus porosus) warming body temperature in sun, Mary River, Northern Territory, Australia

Steven David Miller / Saltwater crocodile (Crocodylus porosus) tail scales just above water surface, Mary River, Northern Territory, Australia