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.

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.

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...

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

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

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

Pal Hermansen / Yelllow dung fly (Scathophaga stercoraria) pair, mating on sheep dung, Lofoten, Norway. June.

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

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 / 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 / Monarch butterflies (Danaus plexippus) resting on trees in wintering grounds in the mountains of central Mexico, El Rosario Butterfly Sanctuary, Michoacan, Mexico.

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 / 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 / Monarch butterflies (Danaus plexippus) covering Fir trees on wintering grounds in the mountains of central Mexico, El Rosario Butterfly Sanctuary, Michoacan, Mexico.

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.)

Guy Edwardes / Spoonwing lacewing (Nemoptera sinuata), warming itself at sunrise, Rhodope Mountains, Bulgaria, June

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 / 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 / Bigclaw crayfish (Faxonius placidus) female oxygenating eggs by fanning them, upper Duck River, Coffee County, Tennessee, USA. Controlled conditions.

Joel Sartore / Photo Ark / Spanish dancer nudibranch (Hexabranchus sanguineus) with an Emperor shrimp (Zenopontonia rex) moving on top of it, Farglory Ocean Park, Hualien. 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 / 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 / Eastern red-tailed hawk (Buteo jamaicensis borealis) looking around and vocalising, Raptor Conservation Alliance in Elmwood, Nebraska, USA. Controlled conditions.

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

Paul Harcourt Davies / Tree lungwort (Lobaria pulmonaria), a large epiphytic lichen consisting of an ascomycete fungus and a green algal partner living together in a symbiotic relationship with a cyanobacterium, growing in...

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

Paul Harcourt Davies / Common blue butterflies (Polyommatus icarus) pair mating on flower, male on the right, Umbria, Italy. May.

Matthew Maran / Red fox siblings (Vulpes vulpes) fighting on an allotment, London, England.

Nick Upton / Spiny mason wasp (Odynerus spinipes) adult female flying to the ornate mud chimney protecting her nest burrow entrance with a Weevil grub (Hypera sp.) she has paralysed to act as food for her larvae,...

Staffan Widstrand / European golden plover (Pluvialis apricaria) calling, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Three Ruff (Philomachus pugnax) males displaying on lek, with two females walking by, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Two Ruff (Philomachus pugnax) males, fighting at lek site with females in background, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Atlantic guillemot (Uria aalge) calling and flapping wings at sunset with colony in background, Hornoya bird cliff island, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Two Ruff (Philomachus pugnax) males, displaying at lek site, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Atlantic guillemot (Uria aalge) pair, in courtship display, with colony in background, Hornoya bird cliff island, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / RF - Red-necked phalarope (Phalaropus lobatus) on water, calling, Varanger Peninsula, Finnmark, Norway. June. (This image may be licensed either as rights managed or royalty free.)

Paul Harcourt Davies / Forester moths (Adscita statices) pair mating, Sibillini, Umbria, Italy. May.

Paul Harcourt Davies / Five Forester moths (Adscita statices) resting on grass stems, with pair mating, Sibillini, Umbria, Italy. May.

Nigel Cattlin / Parasitoid wasp (Aphidius ervi) female, laying eggs through extended ovipositor in Mottled arum aphid (Aulacorthum circumflexum) host pest, England, UK.

Nigel Cattlin / Parasitoid wasp (Diglyphus isaea) female, ovipositing in a Leafminer larva, adult wasps used for biological pest control, England, UK.

Nigel Cattlin / Parasitoid wasp (Diglyphus isaea) female, ovipositing in a Leafminer larva, adult wasps used for biological pest control, England, UK.

Nigel Cattlin / Parasitoid wasp (Praon myzophagum) female, with ovipositor extended, laying eggs in Aphid (Aphidoidea) pest. Biological control in protected crops, England, UK.

Nigel Cattlin / Parasitoid wasp (Aphidius ervi) female, laying eggs with extended ovipositor in aphid host pest, England, UK.

Nigel Cattlin / Parasitoid wasp (Aphidius ervi) female, laying eggs with extended ovipositor in Black bean aphid (Aphis fabae) host pest, England, UK.

Nigel Cattlin / Parasitoid wasp (Aphidius colemani) female, laying eggs through extended ovipositor in Peach potato aphid (Myzus persicae) pest host, England, UK.

Nigel Cattlin / Parasitoid wasp (Aphidius colemani) female, laying eggs through extended ovipositor in Peach potato aphid (Myzus persicae) pest host, England, UK.

Nigel Cattlin / Parasitoid wasp (Aphelinus abdominalis) female, ovipositing in immature Potato aphid (Macrosiphum euphorbiae), England, UK.

Nigel Cattlin / Parasitoid wasp (Aphelinus abdominalis) female, ovipositing in immature Potato aphid (Macrosiphum euphorbiae), England, UK.

Nigel Cattlin / Parasitic wasp (Dacnusa sibirica) female ovipositing in a Leafminer larva in a leaf gallery, England, UK.

Nigel Cattlin / Parasitoid wasp (Aphidius sp.) female, ovipositing in a Peach potato aphid (Myzus persicae), used for biological control in crops, England, UK.

Nigel Cattlin / Parasitoid wasp (Aphidius spp.) female, about to lay eggs in Peach potato aphid (Myzus persicae) with ovipositor pointing forward, England, UK.

Nigel Cattlin / Three Fairyfly parasitoid wasps (Anagrus atomus) ovipositing in the eggs of Tomato leafhopper (Hauptidia maroccana), England, UK.

Nigel Cattlin / Parasitoid wasp (Diaeretiella rapae) female, ovipositig in a Mealy cabbage aphid (Brevicoryne brassicae), a pest of brassica crops, England, UK.

Jack Perks / Three-spined stickleback (Gasterosteus aculeatus) male making a nest. The fish repeatedly swims in and out of the frame with vegetation in its mouth, constructing the nest with this material. UK, June...

Jack Perks / Shoal of Roach (Rutilus rutilus) and Perch (Perca fluviatilis). A Brown trout (salmo trutta) swims into the frame, startling the shoal, as it looks for prey. The fish swims out of the frame. Rutland,...

Jack Perks / Sea trout (Salmo trutta) pair courting, in preparation to spawning. The male quivers near the female and then she uses her tail fin to dig a shallow depression (a redd). Perthshire, UK, November.

Jack Perks / Sea trout (Salmo trutta) pair courting, in preparation to spawning. The female uses her tail fin to dig a shallow depression (a redd) and then the male quivers near her. Perthshire, UK, November.

Jack Perks / Atlantic salmon (Salmo salar) pair courting. The female is digging a redd with her tail fin. The pair display courtship as they prepare to spawn. Perthshire, UK, November.

Jack Perks / Pike (Esox lucius) catching a Mayfly (Ephemeroptera sp.) as it emerges, Hampshire, UK, May.

Jack Perks / Chubs (Squalius cephalus) gathering as they prepare to spawn. A shoal of Minnows (Phoxinus phoxinus) are swimming nearby. Nottinghamshire UK , May.

Jack Perks / Barbel (Barbus barbus) males pushing each other as they prepare to spawn, Nottinghamshire, UK. May.

Jack Perks / Brown trout (Salmo trutta) pair courting. The male quivers near the female and then she uses her tail fin to dig a shallow depression (a redd). Chalk stream, Cambridgeshire, UK. January.

Tony Wu / Elkhorn sculpin (Alcichthys elongatus) male, guarding its brood of bright yellow eggs in a rock crevice, Hokkaido, Japan, Pacific Ocean.

Tim Laman / King penguins (Aptenodytes patagonicus) swimming underwater, Macquarie Island, Subantarctic Island of Australia, Pacific Ocean.

Henley Spiers / Green turtle (Chelonia mydas) juvenile, swimming in open ocean, with two Pilot fish (Naucrates ductor) and a Remora (Echeneidae) swimming alongside, Eastern Pacific Ocean. Endangered.

Guy Edwardes / Hooded crow (Corvus cornix) mobbing a Griffon vulture (Gyps fulvus) perched on branch, Eastern Rhodope Mountains, Bulgaria. January.

Guy Edwardes / Dalmatian pelicans (Pelecanus crispus) flock, squabbling over food on lake, Lake Kerkini, Greece. January.

Espen Bergersen / European herring gull (Larus argentatus) fishing, Andoya, Nordland, Norway. August.

Espen Bergersen / Barnacle goose (Branta leucopsis) resting with chicks nestling among its feathers to keep warm, Svalbard, Norway. July.

Espen Bergersen / Snow bunting (Plectrophenax nivalis) chicks in nest, begging for food, Svalbard, Norway. July.

Espen Bergersen / Long-eared owl (Asio otus) hunting over a wildflower meadow, Troms, Norway. June. Cropped

Danny Green / European stonechat (Saxicola rubicola) male and juvenile perched on a tree stump, the juvenile begging for food, Dumfries and Galloway, Scotland, UK. May.

Danny Green / Northern gannets (Morus) pair, with nesting material in beak, head portrait, Great Saltee Island, Republic of Ireland. May.

Andy Trowbridge / Eastern great egret (Ardea alba modesta) standing in shallow water with fish prey in beak, Lake McGregor, Canterbury, South Island, New Zealand.

Andrew Parkinson / Bengal tiger (Panthera tigris tigris) female juvenile, displaying aggressive behaviour towards its father, Bandhavgarh National Park, India. Endangered.

Mike Read / Eurasian otter (Lutra lutra) cub feeding on Velvet swimming crab (Necora puber) at the edge of Loch Linnhe, Kingairloch, Scotland, UK, May.

Mike Read / Eurasian otter (Lutra lutra) cub feeding on Velvet swimming crab (Necora puber) at the edge of Loch Linnhe, Kingairloch, Scotland, UK, May.

Graham Eaton / Bottlenose dolphin (Tursiops truncatus) surfacing with St Tudwals Islands behind , Abersoch, Gwynedd, Wales, UK, Cardigan Bay, July.

Graham Eaton / Bottlenose dolphin (Tursiops truncatus) surfacing with Llyn Peninsula behind, Abersoch, Gwynedd, Cardigan Bay, May.

Graham Eaton / Bottlenose dolphins (Tursiops truncatus) surfacing, Abersoch, Gwynedd, Wales, UK, Cardigan Bay, May.

Graham Eaton / Bottlenose dolphin (Tursiops truncatus) pod surfacing and swimming under water's surface, with Llyn Peninsula behind, Abersoch, Gwynedd, Wales, UK, Cardigan Bay, May.