Andres M. Dominguez / Eurasian kingfisher (Alcedo atthis) male, perched on branch over pond with tadpole prey in beak, backlit at dawn, Sierra de Grazalema Natural Park, Cadiz, Spain. October.

Andres M. Dominguez / Eurasian kingfisher (Alcedo atthis) male, perched on a rock in pool, backlit at dawn, Sierra de Grazalema Natural Park, Cadiz, Spain. October.

Dr. Axel Gebauer / Aerial view of Red deer (Cervus elaphus) walking through pond with Water caltrop (Trapa natans) and blue bacteria, surrounded by Reedbeds (Phragmites australis), Biosphere Reserve, Upper Lusatia, Pola...

Ann & Steve Toon / Three Giraffes (Giraffa camelopardalis) silhouetted at sunset, Chobe National Park, Botswana.

Doug Gimesy / Grey-headed flying-fox (Pteropus poliocephalus) in flight after dipping into water to cool down and drink, Myuna Wetlands, Doveton, Victoria, Australia.

Doug Gimesy / Little pied cormorant (Microcarbo melanoleucos) standing on intertidal rocks, feeding on fish prey, Port Philip Bay, Victoria, Australia.

Gabriel Rojo / Geoffroy's cat (Leopardus geoffroyi) walking past seaweed covered rocks on beach, Punta Norte Nature Reserve, Peninsula Valdes, Chubut Province, Patagonia, Argentina.

Gabriel Rojo / Geoffroy's cat (Leopardus geoffroyi) walking along beach with Gulls (Larus sp.) in background, Punta Norte Nature Reserve, Peninsula Valdes, Chubut Province, Patagonia, Argentina.

George Sanker / Coyote (Canis latrans) hunting in a wetland meadow in summer, Yellowstone National Park, Wyoming, USA. June.

Jussi Murtosaari / Two Brown bear (Ursus arctos) males, fighting, Finland. August.

Jussi Murtosaari / Fieldfare (Turdus pilaris) perched in Rowan (Sorbus sp.) tree, feeding on berries, Finland. October.

Jussi Murtosaari / Blue-cheeked bee-eater (Merops persicus) perched on branch, Finland. June.

Jussi Murtosaari / Grey wolf (Canis lupus) shaking fur dry after swimming, Finland. August.

Jussi Murtosaari / Bank vole (Clethrionomys glareolus) standing on hind legs, feeding on Strawberry (Fragaria sp.) leaves, Finland. July.

Linda Pitkin / Green turtle (Chelonia mydas) resting on seabed feeding on Seagrass (Halophila stipulacea) with a Remora (Echeneis naucrates) on its back and shoals of small fish swimming around, Marsa Alam, Egypt, R...

Linda Pitkin / Barrel sponge (Xestospongia testudinaria) on reef with shoal of Barracuda (Sphyraena sp.) in background, Tubbataha Reefs Natural Park, Palawan, Philippines, Sulu Sea.

Linda Pitkin / Anthias (Pseudanthias sp.) and Damselfish (Chromis sp.) swimming over coral reef with Acropora (Acropora sp.) corals and Fire coral (Millepora sp.), Tubbataha Reefs Natural Park, Palawan, Philippines,...

Mark Carwardine / European hare (Lepus europaeus) sitting alert at edge of woodland, Hungary. June.

Mark Carwardine / European swallow (Hirundo rustica) flying low over water to drink, Hungary. June.

Mark Carwardine / Humpback whale (Megaptera novaeangliae) surfacing, Antarctic Peninsula, Southern Ocean.

Mark Carwardine / Brown bear (Ursus arctos) female, standing at edge of river, Great Bear Rainforest, British Columbia, Canada. October.

Marie Read / Varied thrush (Ixoreus naevius) male, perched on branch, singing in spring, Eagle River, Alaska, USA. May.

Marie Read / Snow buntings (Plectrophenax nivalis) large flock taking flight in winter, Vermont, USA. January.

Marie Read / Two Pigeon guillemots (Cepphus columba) in flight over rippling water, Haida Gwaii, British Columbia, Canada. May.

Marie Read / Pacific loons (Gavia pacifica) pair in breeding plumage, on water, Anchorage, Alaska, USA. May.

Marie Read / Northern parula (Parula americana) male in breeding plumage, perched in flowering Eastern redbud (Cercis canadensis) in spring, Ohio, USA. April.

Oliver Hellowell / Red squirrel (Sciurus vulgaris) standing on mossy rock in woodland garden, Perthshire, Scotland, UK. September. Cropped.

Oliver Hellowell / Red squirrel (Sciurus vulgaris) sitting upright among heather, in woodland garden, Perthshire, Scotland, UK. September. Cropped.

Oliver Hellowell / Red squirrel (Sciurus vulgaris) sitting on mossy rock in woodland garden, Perthshire, Scotland, UK. September. Cropped.

Oliver Hellowell / Red squirrel (Sciurus vulgaris) standing at base of Pine tree in woodland garden, Perthshire, Scotland, UK. September. Cropped.

Pal Hermansen / Melodius blackbird (Dives dives) attempting to catch a butterfly which is flying behind a plexiglass window, Costa Rica.

Pal Hermansen / Musk ox (Ovibos moschatus) pair mating, Dovrefjell-Sunndalsfjella National Park, Norway. September.

Pal Hermansen / Group of male Toads (Bufo bufo) trying to mate with female, underwater in small lake, Akershus, Norway. May.

Ripan Biswas / Bombay night frog (Nyctibatrachus humayuni) egg cluster, with tadpoles visible inside translucent eggs, on leaf, Amboli, Maharastra, India.

Richard Flack / Böhm's bee-eater (Merops boehmi) perched on thin branch of wild Mango (Mangifera sp.) tree in riparian woodland, Thangadzi River Conservancy, Southern Malawi.

Roger Powell / Red-throated diver (Gavia stellata) male, running over the water at speed and taking flight, Kongsfjordfjellet, Finnmark, Norway. June.

Roger Powell / Two Ruffs (Calidris pugnax) male, fighting at the lek, Pokka, Finland, Lapland. May.

Roger Powell / Two Ruffs (Calidris pugnax) male, fighting at the lek, Pokka, Finland, Lapland. May.

Roger Powell / Four Greylag geese (Anser anser) flying low over lake, East Chevington Reserve, Druridge Bay, Northumberland, UK. November.

Roger Powell / Bearded vulture (Gypaetus barbatus) juvenile, landing among a group of Griffon vultures (Gyps fulvus) at feeding site with a wooded hillside behind, Lamiana, Aragon, Spanish Pyrenees, Spain. April.

Roger Powell / Two Bearded vultures (Gypaetus barbatus) in courtship display over a hillside, immature male trying to talon grapple with a mature female, Lamiana, Aragon, Spanish Pyrenees, Spain. April.

Roger Powell / Two Bearded vultures (Gypaetus barbatus) fighting over food, one with wings spread in threatening posture, Lamiana, Aragon, Spanish Pyrenees, Spain. April.

Sven Zacek / Capercaillie (Tetrao urogallus) male, with some tail feathers missing, lekking at sunset, Tartumaa county, Estonia.

Sven Zacek / Capercaillie (tetrao urogallus) male, lekking perched on top of a Pine tree at dusk, Tartumaa county, Estonia.

Tui De Roy / Green turtles (Chelonia mydas) basking at dusk on beach, probably to kill ectoparasites and seaweed growth on their shells, Maui Island, Hawaii. Endangered.

Tui De Roy / Green turtle (Chelonia mydas) swimming with school of Barracuda (Sphyraena sp.) behind, Cousins Rock, near Santiago Island, Galapagos Islands. Endangered.

Tui De Roy / Group of Green turtles (Chelonia mydas) basking at sunset, probably to kill ectoparasites and seaweed growth on their shells, Maui Island, Hawaii. Endangered.

Tui De Roy / Kemp's ridley turtle (Lepidochelys kempii) female, coming ashore to nest in daylight, Rancho Nuevo Beach, Tamaulipas, Mexico. Critically endangered.

Tui De Roy / Kemp's ridley turtle (Lepidochelys kempii) female, coming ashore to nest in daylight, Rancho Nuevo Beach, Tamaulipas, Mexico. Critically endangered.

Staffan Widstrand / RF - Two Ruffs (Philomachus pugnax) male, fighting at lek site, Varanger Peninsula, Finnmark, Norway. June. (This image may be licensed either as rights managed or royalty free.)

Staffan Widstrand / RF - Atlantic guillemot (Uria aalge) standing on rock spreading its wings at sunset, with colony behind, Hornoya bird cliff Island, Vardoe, Varanger Peninsula, Finnmark, Norway. June. (This image may...

Staffan Widstrand / RF - Atlantic puffin (Fratercula arctica) portrait, Hornoya bird cliff Island, Vardoe, Varanger Peninsula, Finnmark, Norway. June. (This image may be licensed either as rights managed or royalty free....

Terry Whittaker / Atlantic puffin (Fratercula arctica), Grimsey Island, Iceland, June.

Guy Edwardes / European pond turtle/terrapin (Emys orbicularis) swimming in pond with head above water and a fly resting on its snout, near Bratsigovo, Bulgaria, May

Joel Sartore / Photo Ark / Blunt-nosed leopard lizard (Gambelia sila) looking around. The animal leaves the frame. Fresno Chaffee Zoo, California. Captive.

Joel Sartore / Photo Ark / Close up of a Timber rattlesnake's (Crotalus horridus) tail. It is vibrating its tail as a threat display. Verve Biotech, Waverly, Nebraska. Captive.

Joel Sartore / Photo Ark / Timber rattlesnake (Crotalus horridus) performing threat display by vibrating tail, Verve Biotech, Waverly, Nebraska. Captive.

Joel Sartore / Photo Ark / Timber rattlesnake (Crotalus horridus) performing threat display by vibrating tail, Verve Biotech, Waverly, Nebraska. Captive.

Joel Sartore / Photo Ark / Grandidier's mongoose / Grandidier's vontsira (Galidictis grandidieri) looking around, Al Bustan Zoological Centre. Captive. Endangered.

Joel Sartore / Photo Ark / Eastern quoll (Dasyurus viverrinus) lying down and looking at the camera, Zoo Leipzig. Captive. Endangered.

Joel Sartore / Photo Ark / Proboscis monkey (Nasalis larvatus) male using its hands to pick food up and eat. The animal leaves the frame. Taman Safari Prigen. Captive. Endangered.

Joel Sartore / Photo Ark / Hawaiian monk seal (Neomonachus schauinslandi) vocalising. The animal's head appears from bottom of the frame. Minnesota Zoo. Captive. Endangered.

Joel Sartore / Photo Ark / Marbled cat (Pardofelis marmorata longicaudata) looking towards the camera and lying down. The animal hisses and bares its teeth. Al Bustan Zoological Centre, Sharjah. Captive.

Joel Sartore / Photo Ark / San Bernardino kangaroo rat (Dipodymys merriami parvus) looking at the camera, then the animal partially leaves frame, San Diego Zoo Safari Park, Escondido, California. Captive. Federally endangered.

Joel Sartore / Photo Ark / Slender-horned gazelle (Gazella leptoceros) appearing from bottom of frame and looking around, San Diego Zoo Safari Park. Captive. Endangered.

Joel Sartore / Photo Ark / Okapi (Okapia johnstoni) juvenile male, two months old, flicking a fly off its face with its tongue. Leucistic individual, named 'Mzimu' (meaning ghost in Swahili), Al Bustan Zoological Centre, Sharja...

Joel Sartore / Photo Ark / Okapi (Okapia johnstoni) juvenile male, two months old, standing and looking around. Leucistic individual, named 'Mzimu' (meaning ghost in Swahili), Al Bustan Zoological Centre, Sharjah. Captive. Enda...

Joel Sartore / Photo Ark / Eastern black bear (Ursus americanus americanus) juvenile, four months old, looking at the camera and moving curiously towards the camera, North Carolina Zoo Wildlife Rehabilitation Center, USA. Contr...

Joel Sartore / Photo Ark / Common topknot (Zeugopterus punctatus) moving its fins, Aquazoo Loebbecke Museum, Dusseldorf. Captive.

Joel Sartore / Photo Ark / Close up of a Common topknot (Zeugopterus punctatus) head. The animal is looking at the camera. Aquazoo Loebbecke Museum, Dusseldorf. Captive.

Joel Sartore / Photo Ark / Close up of a Coral grouper (Cephalopholis miniata) head. The animal looks around. Oklahoma Aquarium. Captive.

Joel Sartore / Photo Ark / Bigmouth chub (Nocomis platyrhynchus) looking around, Aquatic Wildlife Conservation Center, Marion, Virginia. Captive.

Joel Sartore / Photo Ark / Buffalo darter (Ehtheostoma bison), Brush Creek, Lewis County, Tennessee, USA. Controlled conditions.

Joel Sartore / Photo Ark / Sulawesi white-collared kingfisher (Todiramphus chloris) defecating, San Diego Zoo. Captive.

Joel Sartore / Photo Ark / Two Macqueen's bustard (Chlamydotis macqueenii) chicks, four days old. One chick pecks the other and then walks forward. National Avian Research Center, Abu Dhabi. Captive.

Joel Sartore / Photo Ark / Great hornbill (Buceros bicornis) looking around, Al Bustan Zoological Centre, Sharjah. Captive.

Joel Sartore / Photo Ark / Blyth's tragopan (Tragopan blythii) male looking around, San Diego Zoo. Captive.

Joel Sartore / Photo Ark / Great argus (Argusianus argus) male walking around, in and out of the frame, Pheasant Heaven. Captive.

Joel Sartore / Photo Ark / Delacour's crested fireback (Lophura ignita macartneyi) male looking around, Pheasant Heaven. Captive.

Joel Sartore / Photo Ark / Victoria crowned pigeon (Goura victoria) looking around with its crest raised, Pheasant Heaven. Captive.

Joel Sartore / Photo Ark / Western burrowing owl (Athene cunicularia hypugaea) walking into and across the frame. The animal looks around and then walks back out of the frame. Raptor Conservation Alliance, Elmwood, Nebraska, US...

Joel Sartore / Photo Ark / Red bird-of-paradise (Paradisaea rubra) male looking around and vocalising, Walsrode Bird Park. Captive.

Joel Sartore / Photo Ark / Magnificent bird-of-paradise (Cicinnurus magnificus) looking around and vocalising, Private collection, Heilbronn. Captive.

Joel Sartore / Photo Ark / King bird-of-paradise (Cicinnurus regius) male curiously looking at the camera and then vocalising. Walsrode Bird Park. Captive.

Joel Sartore / Photo Ark / Indochinese green magpie (Cissa hypoleuca) female looking around. The animal performs bubbling with throat. Los Angeles Zoo & Botanical Gardens. Captive.

Joel Sartore / Photo Ark / Eastern red-tailed hawk (Buteo jamaicensis borealis) looking around and vocalising, Raptor Conservation Alliance in Elmwood, Nebraska, USA. Controlled conditions.

Joel Sartore / Photo Ark / Indochinese green magpie (Cissa hypoleuca) female looking around, Los Angeles Zoo & Botanical Gardens. Captive.

Joel Sartore / Photo Ark / Sooty falcon (Falco concolor) looking round. Then the animal ruffles its feathers and preens itself. Private collection, Dubai. Captive.

Joel Sartore / Photo Ark / Shaheen peregrine falcon (Falco peregrinus peregrinator) looking around and vocalising, private collection, Dubai. Captive.

Joel Sartore / Photo Ark / Red-capped peregrine falcon (Falco peregrinus babylonicus) looking around and vocalising, private collection, Dubai. Captive.

Joel Sartore / Photo Ark / Eastern red-tailed hawk (Buteo jamaicensis borealis) looking around. This individual is leucistic. Raptor Conservation Alliance, Elmwood, Nebraska. Controlled conditions.

Joel Sartore / Photo Ark / Siberian crane (Leucogeranus leucogeranus) female looking around, then the animal lowers its head and ruffles its feathers. International Crane Foundation, Baraboo, Wisconsin. Controlled condiitons. C...

Joel Sartore / Photo Ark / Northern bald ibis (Geronticus eremita) looking around, Houston Zoo. Captive. Endangered.

Joel Sartore / Photo Ark / Red-fan parrot (Deroptyus accipitrinus) displaying and curiouly looking at the camera, Houston Zoo. Captive.

Joel Sartore / Photo Ark / Mountain yellow-legged frog (Rana muscosa) looking at the camera, then the animal jumps out of the frame. Oakland Zoo, California. Captive. Endangered.

Joel Sartore / Photo Ark / Wattled lapwing (Vanellus senegallus) looking around. The animal raises and ruffles its feathers. Walsrode Bird Park. Captive.