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.

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 along beach with Gulls (Larus sp.) in background, Punta Norte Nature Reserve, Peninsula Valdes, Chubut Province, Patagonia, Argentina.

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.

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

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.

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

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.

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.

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

Joel Sartore / Photo Ark / Northern rockhopper penguin (Eudyptes moseleyi) appearing from the bottom of the frame and then looking around, Calgary Zoo. Captive. Endangered.

Paul Harcourt Davies / Woodlark (Lullula arborea) eggs in nest, Campo Imperatore, Abruzzo, Italy. June.

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.)

Staffan Widstrand / Brambling (Fringilla montifringilla) perched on branch, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Oystercatcher (Haematopus ostralegus) walking over pebbles on the shore, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Northern hawk owl (Surnia ulula) perched on branch, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Whimbrel (Numenius phaeopus) portrait, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Long-tailed skua (Stercorarius longicaudus) standing on wet ground, Varanger Peninsula, Finnmark, Norway. June.

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

Staffan Widstrand / Willow ptarmigan grouse (Lagopus lagopus) standing on a rock, Varanger Peninsula, Finnmark, Norway. November.

Staffan Widstrand / Red-necked phalarope (Phalaropus lobatus) on water, Varanger Peninsula, Finnmark, Norway.

Staffan Widstrand / Greenfinch (Carduelis chloris) in flight, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Whimbrel (Numenius phaeopus) standing on stony ground, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Atlantic puffin (Fratercula arctica) head portrait, Hornoya bird cliff island, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Arctic skua (Stercorarius parasiticus) in flight, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Kittiwake (Rissa tridactyla) portrait, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Whimbrel (Numenius phaeopus) portrait, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Hoary redpoll (Acanthis hornemanni) perched on dead tree trunk, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Bar-tailed godwit (Limosa lapponica) portrait, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Red-necked phalarope (Phalaropus lobatus) on water, 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 / Shags (Phalacrocorax aristotelis) flock perched on cliff top at sunset, Hornoya bird cliff island, 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 / Arctic skua (Stercorarius parasiticus) portrait, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Shag (Phalacrocorax aristotelis) head portrait, Hornoya bird cliff island, 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 - Whimbrel (Numenius phaeopus) portrait, Varanger Peninsula, Finnmark, Norway. June. (This image may be licensed either as rights managed or royalty free.)

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

Staffan Widstrand / RF - European golden plover (Pluvialis apricaria) portrait, Varanger Peninsula, Finnmark, Norway. June. (This image may be licensed either as rights managed or royalty free.)

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 / View of the ancient city of Orvieto surrounded by orchards and Cherry (Prunus avium) trees growing along path, viewed in spring from the north side, Orvieto, Umbria, Italy. March, 2017.

Paul Harcourt Davies / Peacock (Pavo sp.) feather, close up showing iridescence, 10x magnification.

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

Sven Zacek / Whooper swan (Cygnus cygnus) standing in flooded river meadow during spring flooding, Alam-Pedja Nature Reserve Tartumaa county, Southern Estonia.

Sven Zacek / Great grey owl (Strix nebulosa) perched on branch at dusk, Southern Estonia.

Sven Zacek / Great grey owl (strix nebulosa) perched on Birch (Betula pendula) branch defecating, Southern Estonia.

Russell Laman / Emperor penguin (Aptenodytes forsteri) leaping from the sea onto ice, Cape Colbeck, Ross Sea, Antarctica.

Russell Laman / Southern royal albatross (Diomedea epomophora) in flight over the ocean with the rising full moon in the sky above, Campbell Island, New Zealand Sub Antarctic Islands.

Lorraine Bennery / Three Malagasy sacred ibis (Threskiornis bernieri) perched in tree in mangroves, Betsiboka river, Majunga area, Madagascar. Endangered.

Konrad Wothe / Dipper (Cinclus cinclus) flying through waterfall, Bavaria, Germany. May.

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 / Four Herring gulls (Larus argentatus) in flight, one with remains of a Herring in its beak, being chased by the other three, Skjervoy, Troms, Norway, Norwegian Sea. October

Espen Bergersen / Fieldfare (Turdus pilaris) perched in Rowan (Sorbus aucuparia) tree, feeding on berries, Troms, Norway. October.

Espen Bergersen / Common starling (Sturnus vulgaris) perched in Rowan (Sorbus aucuparia) tree, feeding on berries, Troms, Norway. October. Cropped