Richard Du Toit / Cattle Egret (Bubulcus ibis) on Burchell's Zebra (Equus burchellii), Rietvlei Nature Reserve, Gauteng, South Africa

Juan Carlos Munoz / Bearded vulture (Gypaetus barbatus) in flight. Ordesa National Park, Spanish Pyrenees, April.

Juan Carlos Munoz / Bearded Vultures (Gypaetus barbatus) juvenile (left) and adult fighting in flight. Simien National Park, Ethiopia, Africa.

Juan Carlos Munoz / Bearded vulture (Gypaetus barbatus) chasing Thick-billed Raven (Corvus crassirostris) in flight. Simien National Park, Ethiopia, Africa.

Fergus Gill / 2020VISION / Snow Butning (Plectrophenax nivalis) Searching for food in a snow storm. Cairngorms National Park

Uri Golman / Asiatic lion cub (Panthera leo persica) looking up into tree, possibly at a bird, Gir Forest NP, Gujarat, India

Ben Hall / 2020VISION / Red grouse (Lagopus lagopus scoticus) on heather moorland showing habitat, Peak District National Park, UK, September. Did you know? Red grouse thrive on managed moorlands the UK has at least 155,000...

Sandesh Kadur / Indian / Asian one-horned rhinoceros (Rhinoceros unicornis) approaching, Kaziranga National Park, Assam, India

Steve Gettle / Sharp-tailed Grouse (Tympanuchus phasianellus) male displaying at lek, Seney National Wildlife Refuge, Michigan

Mark Hamblin / 2020VISION / Black grouse (Tetrao tetrix) male at lek, Creag Megaidh NNR, Highlands, Scotland, UK, April

Pete Oxford / Sword-billed Hummingbird (Ensifera ensifera), the only species of bird to have a bill longer than the rest of its body, approaching a flower. Yanacocha Reserve, Ecuador.

Pete Oxford / Silhouette of a Sword-billed Hummingbird (Ensifera ensifera), the only species of bird to have a bill longer than the rest of its body. Yanacocha Reserve cloud forest, Ecuador.

Inaki Relanzon / Bearded vulture (Gypaetus barbatus) in flight against snowy mountains. Ordesa National Park, Aragon, Spain, November 2010.

Peter Cairns / 2020VISION / Three Rock ptarmigan (Lagopus mutus) perched on rock, camouflaged against snow in winter plumage, Cairngorms NP, Highlands, Scotland, UK, February. Did you know? The ptarmigan is the only British bird...

Fergus Gill / Red grouse (Lagopus lagopus scoticus), portrait of a cock bird displaying to rival males. Cairngorms National Park, Scotland, April

Fergus Gill / Red grouse (Lagopus lagopus scoticus), portrait of a cock bird. Cairngorms National Park, Scotland, April

Chien Lee / Lilac-cheeked Kingfisher (Cittura cyanotis), Tangkoko Nature Reserve, Sulawesi, Indonesia

Angelo Gandolfi / Carrion Crows (Corvus corone) mobbing a Bearded vulture (Gypaetus barbatus) Scala di St. Regina gorges. Corte, Parc Naturel Regional de Corse, Corsica island, France, January

Angelo Gandolfi / Bearded vulture (Gypaetus barbatus) in flight over rocky outcrops, Monte Incudine, Parc Naturel Regional de Corse, Corsica island, France, February

John Waters / Golden eagle (Aquila chrysaetos) adult female taking off, flying over mountain landscape, trained bird photographed during filming in Glenveagh National Park, Donegal, Republic of Ireland. August 2010

John Waters / Golden eagle (Aquila chrysaetos) adult female taking off, flying over mountain landscape, trained bird photographed during filming in Glenveagh National Park, Donegal, Republic of Ireland. August 2010

Winfried Wisniewski / African Fish Eagle (Haliaeetus vocifer) striking at fish, Chobe National Park, Botswana

Winfried Wisniewski / Sandhill Crane (Grus canadensis) pair flying, Bosque del Apache National Wildlife Refuge, New Mexico

Steve Gettle / Cape May Warbler (Setophaga tigrina) male calling, Crane Creek State Park, Ohio

Steve Gettle / Chestnut-sided Warbler (Setophaga pensylvanica) male, Crane Creek State Park, Ohio

Yva Momatiuk & John Eastcott / Cape Buffalo (Syncerus caffer) bull with Red-billed Oxpecker (Buphagus erythrorhynchus) pair, Masai Mara National Reserve, Kenya

Donald M. Jones / Purple Gallinule (Porphyrio martinicus), Everglades National Park, Florida

Pete Oxford / Black-chested Buzzard-Eagle (Geranoaetus melanoleucus) juvenile, Podocarpus National Park, Ecuador

Vincent Grafhorst / Cape Teal (Anas capensis) standing in shallow water, Gaborone Game Reserve, Botswana

Anup Shah / Lilac-breasted roller (Coracias caudata) perched on the back of a Common zebra (Equus quagga). Masai Mara National Reserve, Kenya. December

Konrad Wothe / Hoatzin (Opisthocomus hoazin) in rainforest, Tambopata National Reserve, Peru

Wild Wonders of Europe / Hermansen / Bird's foot trefoil (Lotus corniculatus) flower, Burren National Park, County Clare, Republic of Ireland, June 2009

Wild Wonders of Europe / Benvie / Bird's nest orchid (Neottia nidus-avis) in flower, France, Queyras Natural Park, May 2009

Tim Laman / Male Victoria's Riflebird (Ptiloris victoriae) bird of paradise perched, calling on display perch. Atherton Tablelands, Wooroonooran National Park, Queensland, Australia.

Richard Du Toit / Hippopotamus (Hippopotamus amphibius) male with Red-billed Oxpecker (Buphagus erythrorhynchus) pair on back, Chobe National Park, Botswana

Nick Garbutt / Close up of feathers of Male Malayan peacock pheasant (Polyplectron malacense) from primary lowland rainforest areas of Malaysia, Vulnerable species. Captive, Jurong Bird Park, Singapore..

Sebastian Kennerknecht / Bald Eagle (Haliaeetus leucocephalus) at sunrise, Lower Klamath National Wildlife Refuge, California

Sebastian Kennerknecht / Snowy Plover (Charadrius nivosus) in winter plumage on beach, Point Reyes National Seashore, California

Kevin Schafer / Red-breasted Toucan (Ramphastos dicolorus) calling, Itatiaia National Park, Brazil

Ingo Arndt / Ostrich (Struthio camelus) female chasing away rival, Masai Mara National Reserve, Kenya

Ingo Arndt / African Jacana (Actophilornis africana) foraging near Hippopotamus (Hippopotamus amphibius) amid water lettuce, Masai Mara National Reserve, Kenya

Thomas Marent / Andean Cock-of-the-rock (Rupicola peruvianus) male, Manu National Park, Peru

Thomas Marent / Eclectus Parrot (Eclectus roratus) male calling, Daintree National Park, Australia

Winfried Wisniewski / Great White Pelican (Pelecanus onocrotalus), Lake Nakuru, Lake Nakuru National Park, Kenya

Winfried Wisniewski / Lesser Flamingo (Phoenicopterus minor) pair flying, Lake Nakuru National Park, Kenya

Theo Allofs / Lechwe (Kobus leche) and Cattle Egret (Bubulcus ibis) in Moremi Game Reserve, Okavango Delta, Botswana

Mitsuaki Iwago / Cape Buffalo (Syncerus caffer) eyeing Red-billed Oxpecker (Buphagus erythrorhynchus), Serengeti National Park, Tanzania

Richard Du Toit / Burchell's Zebra (Equus burchellii) and Carmine Bee-eater (Merops nubicus) as passenger, Savuti, Chobe National Park, Botswana

Yva Momatiuk & John Eastcott / California Condor (Gymnogyps californianus) adult with wingspan of 9 feet flying, critically endangered, bred in captivity, later released, and wearing radio transmitter, near Zion National Park, Utah

Mark Moffett / Granular Poison Dart Frog (Dendrobates granuliferus) portrait on bird's nest fungus, Corcovado National Park, Costa Rica

Mitsuaki Iwago / African Elephant (Loxodonta africana) bull with ears out in defensive posture, Serengeti National Park, Tanzania

Mitsuaki Iwago / Black Rhinoceros (Diceros bicornis) with Red-billed Oxpecker (Buphagus erythrorhynchus), Serengeti National Park, Tanzania

Richard Du Toit / Red-billed Oxpecker (Buphagus erythrorhynchus) on Impala (Aepyceros melampus) male, Kruger National Park, South Africa

Mitsuaki Iwago / Hippopotamus (Hippopotamus amphibius) with Yellow-billed Oxpecker (Buphagus africanus), Serengeti National Park, Tanzania

Gerry Ellis / Hippopotamus (Hippopotamus amphibius) swimming in water lettuce, with Cattle Egret (Bulbulcus ibis) perched on head, Serengeti National Park, Tanzania

Tom Vezo / Sandhill Crane (Grus canadensis) adult flying, Bosque del Apache National Wildlife Refuge, New Mexico

Richard Du Toit / African openbill storks silhouetted at sunset {Anastomus lamelligerus} Chobe NP, Botswana, Africa

Michael & Patricia Fogden / White-necked Jacobin (Florisuga mellivora) hummingbird male feeding on nectar from a Bromeliad flower, La Selva Biological Research Station, Rainforest, Costa Rica

Thomas Mangelsen / White Ibis (Eudocimus albus) trio feeding at sunset, Ding Darling National Wildlife Refuge, Sanibel Island, Florida

Tim Fitzharris / Sandhill Crane (Grus canadensis) flying, Bosque Del Apache, New Mexico

Yva Momatiuk & John Eastcott / Black-bellied Plover (Pluvialis squatarola) non-breeding bird resting on one leg on shore, spring, Gulf of Mexico, Padre Island National Seashore, Texas

Thomas Mangelsen / Peregrine Falcon (Falco peregrinus) flying, Wager Bay, Northwest Territories, Canada

Thomas Mangelsen / Florida Jay (Aphelocoma coerulescens) perching in tree, Oscar Schever State Park, Florida

Yva Momatiuk & John Eastcott / Sandhill Crane (Grus canadensis) flocks congregating before flying south in autumn, Denali National Park and Preserve, Alaska

Tom Vezo / American White Pelican (Pelecanus erythrorhynchos) landing in water, Everglades National Park, Florida

Gerry Ellis / Greater Roadrunner (Geococcyx californianus), Bosque del Apache National Wildlife Refuge, New Mexico

Konrad Wothe / Red-crowned Crane (Grus japonensis) flock feeding in snow, Tsurui Ito Sanctuary, Japan

Sumio Harada / American Robin (Turdus migratorius) newly-hatched day old chicks begging in nest with unhatched blue egg, Glacier National Park, Montana

Gerry Ellis / Great Bowerbird (Chlamydera nuchalis) male in courting bower, Katherine Gorge National Park, Australia

Gerry Ellis / Greater Flamingo (Phoenicopterus ruber) nesting colony with mud nests, Inagua National Park, Bahamas

Tim Fitzharris / Bald Cypress (Taxodium distichum) at upper Blue Basin, this is a major migratory bird stopover for the Mississippi Flyway, Reelfoot National Wildlife Refuge, Tennessee

Tui De Roy / Scarlet Macaw (Ara macao) flying in rainforest canopy, upper Tambopata River, Peruvian Amazon, Peru

Tui De Roy / Scarlet Macaw (Ara macao) pair perched on tree limb, originally hand raised by the research center, they are now living in the rainforest canopy, Tambopata-Candamo Reserve, Amazon Basin, Peru

Michael Quinton / Common Raven (Corvus corax) checking out tourist, Yellowstone National Park, Wyoming

Michael Quinton / Common Raven (Corvus corax) using its beak to open a snowmobile's storage compartment in search of food, Yellowstone National Park, Wyoming

Tui De Roy / Blue and Yellow Macaw (Ara ararauna) mixed flock sharing Erythrina tree with Mealy Parrot (Amazona farinosa) flock, Tambopata-Candamo Reserved Zone, Amazon basin, Peru

Jim Brandenburg / Tundra Swan (Cygnus columbianus) flock taking off from lake, Mattamuskeet National Wildlife Reserve, North Carolina

Shin Yoshino / Flamingo (Phoenicopterus sp) flock flying at sunrise, Nalsarovar Bird Sanctuary, India

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) gulp feeding with Herring Gulls (Larus argentatus) waiting for leftovers, Stellwagen Bank National Marine Sanctuary, Massachusetts

Tui De Roy / Sulawesi Red-knobbed Hornbill (Aceros cassidix) male delivering figs to a female sealed inside hollow nest cavity, Tangkoko Dua Saudara Nature Reserve, Sulawesi, Indonesia

Jim Brandenburg / American Darter (Anhinga anhinga) portrait, Everglades National Park, Florida

Jim Brandenburg / Snowy Egret (Egretta thula) flying over water, Ding Darling National Wildlife Refuge, Florida

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) feeding, with Herring Gulls (Larus argentatus) waiting for leftovers, Stellwagen Bank National Marine Sanctuary, Massachusetts

Tui De Roy / Bare-faced Curassow (Crax fasciolata) male in typical Cerrado habitat, Emas National Park, Brazil

Tui De Roy / Scarlet Macaw (Ara macao) pair making a living in rainforest canopy, originally hand-raised by research center, Tambopata-Candamo Reserved Zone, Amazon Basin, Peru

Mitsuaki Iwago / Ostrich (Struthio camelus) male and two females running, Serengeti National Park, Tanzania

Jim Brandenburg / Snowy Egret (Egretta thula) flying, Ding Darling National Wildlife Refuge, Sanibel Island, Florida

Hanne & Jens Eriksen / Falconer with bird Al Areen Park, Manama, Bahrain

Richard Du Toit / Kori bustard {Choriotis kori} with Carmine bee-eater {Merops nubicus} on back. Botswana

Phil Savoie / Raggiana bird of paradise (Paradisaea raggiana) male displaying to female, Papua New Guinea, Varirata NP.

Phil Savoie / Raggiana bird of paradise (Paradisaea raggiana) male displaying at lek Papua New Guinea, Varirata NP.

Georgette Douwma / Grey squirrel {Sciurus carolinensis} taking nuts from bird feeder, Regents Park, London, UK

Tony Heald / African skimmer skimming {Rynchops flavirostris} Chobe NP, Botswana