Sandra Bartocha / Mute Swans (Cygnus olor) flying in formation, Germany, January

Rob Jordan / 2020VISION / Arctic tern (Sterna paradisaea) in flight, Inner Farne, Farne Islands, Northumberland, June.

Gerrit Vyn / Aerial view of large flock of molting Brant. These geese have found refuge on a shallow lake. During their summer moult the geese are flightless. The Teshekpuk Lake area is the most important goose m...

Andy Rouse / Nile crocodile (Crocodylus niloticus) chasing Wildebeest (Connochaetes taurinus) during migration crossing, Masai Mara, Kenya, Africa

Richard Du Toit / Aerial view of herd of African buffalo (Syncerus caffer) on the move, Okavango delta, Botswana

Roger Powell / European Cuckoo (Cuculus canorus) perched on branch, resting briefly whilst on migration north, Castro Verde, Portugal, April

Steven Kazlowski / Thousands of Snow geese (Chen caerulescens) taking flight to begin their migration south from their summer nesting grounds in the Arctic, Alaska.

Eric Baccega / Three Beluga / White Whale (Delphinapterus leucas) swimming at the sea surface during spring migration. Baffin Island, Lancaster sound, Nunavut, Canada, June.

Fabio Liverani / Research scientist releases ringed Yellow wagtail at field research station for the study of bird migration, Ventotene, Pontine Islands, Italy 2008

Eric Dragesco / A large herd of Tien Shan Argali (Ovis ammon karelini) making tracks through snow. Naryn National Park, Kyrgyzstan, Central Asia, November.

Michel Roggo / Sockeye / Red Salmon (Oncorhynchus nerka) on spawning migration. Adams River, British Columbia, Canada, October.

Juergen Freund / Masses of Christmas Island Red Crabs spawning on the beach.

Barrie Britton / Demoiselle cranes {Anthropoides virgo} on migration flying over the Himalayas, Nepal, c 2004

Markus Varesvuo / Swallow (Hirundo rustica) flying low over water, Israel, March

Angelo Gandolfi / Birdwatchers observing White Storks (Ciconia ciconia) in flight over the Strait of Gibraltar. Mirador El Estrecho, Andalusia, Spain, 2007.

Frederique Olivier / Emperor penguin (Aptenodytes forsteri) procession crossing newly formed sea ice on the way to their breeding grounds, Emperor penguin Antarctica, March.

Philippe Clement / Sandhill cranes {Grus canadensis} flying in formation during migration over Denali NP, Alaska, USA.

Stephen Dalton / Monarch butterfly (Danaus plexippus) female in flight. Did you know? Monarch buttterflies migrate up to 2500 miles from Mexico to Canada.

Hanne & Jens Eriksen / Eurasian wryneck (Jynx torquilla) feeding on ground, during spring migration, Oman, April.

Inaki Relanzon / Migrating wildebeest (Connochaetes taurinus) observed from a hot-air balloon, Masai Mara National Reserve, Kenya, Africa. August 2009

David Tipling / Migrant Reed warbler on passenger on boat {Acrocephalus scirpaceus} Bay of Biscay

Solvin Zankl / Norway lemmings roadkill {Lemmus lemmus} Norway

George Chan / A Kazakh family following ancient migration routes, bringing their possessions and livestock down from the Altai mountains of Xinjiang Province, north-west China. February 2007

Markus Varesvuo / Flock of Eurasian Jackdaw (Corvus monedula) in flight, migration, Hanko, Finland, October

Mike Read / Common crane (Grus grus) group in flight, Hortobagy National Park, Hungary, November

David Tipling / Wood Warbler (Phylloscopus sibilatrix) migrant, BirdLife Malta Springwatch Camp, Malta, April

TOM MANGELSEN / Whooping cranes fly over Canada (Grus americana) Saskatchewan

DAVID TIPLING / Sandhill cranes {Grus canadensis} at sunrise, Bosque del Apache, NM, USA

Jeff Rotman / Barrel jellyfish {Rhizostoma octopus} indicates plankton migration, Irish Sea, UK

Jeff Vanuga / Pronghorn antelope herd {Antilocapra americana} migrating through snow, Wyoming,

Doug Wechsler / Monarch butterfly with tagged wing - migration study (Danaus plexippus) New Jersey USA

Doug Wechsler / Monarch butterflies feeding on Ivy, New Jersey, USA. On southbound migration.

Kim Taylor / Migratory locust {Locusta migratoria} on sedge

Staffan Widstrand / Caribou migration male crossing river {Rangifer tarandus} Kobuk Valley NP, Alaska, USA.

Nick Garbutt / Wildebeest (Connochaetes taurinus) crossing river on migration, East Africa

PREMAPHOTOS / Pioneer white butterflies (Anaphaeis / Belenois aurota) drinking from damp ground in desert while on migration, South Africa

Fabio Liverani / Research scientist checks bird net at field research station for the study of bird migration, Ventotene, Pontine Islands, Italy~ 2008

Bruno D'Amicis / Sand martins (Riparia riparia) perched on reed over water during spring migration, Central Morocco, NW Africa

Markus Varesvuo / Black stork (Ciconia nigra) in flight, Tarifa, Spain, September

Markus Varesvuo / Flock of Black kite (Milvus migrans) in flight, Tarifa, Spain, September

Markus Varesvuo / Honey buzzard (Pernis apivorus) in flight on migration, Tarifa, Spain, September

Markus Varesvuo / Flock of White Stork (Ciconia ciconia) in flight on migration, Spain, September

Nick Upton / Silhouetted Common / Eurasian cranes (Grus grus) flying from roost at dawn past full moon, during autumn migration period, Rugen-Bock-region, Mecklenburg-Vorpommern, Germany, October

Nick Upton / Migrating cranes (Grus grus) flying high over Marburg, Hesse, Germany, October

Paul Harcourt Davies / Painted Lady butterfly (Vanessa cardui) at rest, feeding on nectar. Part of the migration of 2009 photographed on Mt terminillo at 2000m. Apennine mountains, Italy, Europe.

Gerrit Vyn / Winter flock of Red-winged Blackbirds (Agelaius phoeniceus) flying low over fields Lower Klamath National Wildlife Refuge, Siskiyou County, California, USA, December.

Bryan and Cherry Alexander / Trains of Nenets Reindeer / Caribou (Rangifer tarandus) on the tundra during spring migration. Yamal, Siberia, Russia, 1993.

Eric Baccega / Large flock of Snow Geese (Chen caerulescens) in flight. Quebec, Canada, January.

Markus Varesvuo / Long-tailed Duck (Clangula hyemalis) silhouetted against late evening sunlit clouds. Porvoo, Finland, May. Magic Moments book plate, page 124.

Brent Stephenson / Barn Swallows (Hirundo rustica) perched on the railing of a cruise ship during a crossing of the Gulf of Mexico, Caribbean Sea, September.

Bryan and Cherry Alexander / Migrating Nenets sled Reindeer / Caribou (Rangifer tarandus) grazing during a rest. Yamal Peninsula, Siberia, Russia, 1993. 40 BELOW bookplate.

Terry Whittaker / 2020VISION / Flock of Dark-bellied brent geese (Branta bernicla) flying across the setting sun, Wallasea Island RSPB reserve, River Crouch, Essex, UK, March 2011

Ernie Janes / Flock of Black-tailed godwit (Limosa limosa) in flight, winter plumage, Norfolk, UK, March

Konrad Wothe / Flock of Snow Geese (Chen caerulescens atlanticus / Chen caerulescens) in flight and on ground at wintering area, Bosque del Apache, New Mexico, USA, November

Markus Varesvuo / Male Blackcap (Sylvia atricapilla) resting after migration, Uto, Finland, May

Gerrit Vyn / Black footed albatross (Phoebastria nigripes) soaring over the open ocean, Gray's Harbor County, Washington, USA October

Yukihiro Fukuda / Japanese giant salamander (Andrias japonicus) moving upstream to spawn, Japan, August

David Pattyn / Common cranes (Grus grus) flock flying against sky at sunrise, Pruchten, Germany, October

Loic Poidevin / Grizzly bear (Ursus arctos horribilis) salmon fishing in river rapids, Katmai National Park, Alaska, USA

Marie Read / Wilson's Phalaropes (Phalaropus tricolor) large flock swimming/foraging near the shoreline at Mono Lake, tufa formations in the background, late July, Mono Lake, California, USA. July.

Marie Read / Tundra Swans (Cygnus columbianus) flock in flight during winter/spring migration. New York, USA, March.

Michel Roggo / Sockeye / Red Salmon (Oncorhynchus nerka) on spawning migration. Adams River, British Columbia, Canada, October.

Markus Varesvuo / Common Starling (Sturnus vulgaris) flock with Baltic Sea in the background, Falsterbo, Sweden, October

Nick Garbutt / Arctic tern (Sterna Paradisaea) hovering in flight over an iceberg.Peterman Island, Antarctic Peninsula, Antarctica. February.

Mark MacEwen / Chinook / King salmon (Oncorhynchus tshawytscha) jumping at Brooks River falls, Katmai National Park, Alaska, July.

Mark MacEwen / Chinook / King salmon (Oncorhynchus tshawytscha) jumping at Brooks River falls, migrating upstream, Katmai National Park, Alaska, July.

Michel Roggo / Atlantic salmon (Salmo salar) in holding pool on upstream spawning migration, Quebec, Canada, August. Taken for the Freshwater Project.

Juan Carlos Munoz / Large group of Straw-coloured fruit bats (Eidolon helvum) in flight during migration, Kasanka National Park, Serenje, Zambia, Africa

Denis-Huot / Wildebeest (Connochaetes taurinus) herd swimming across Mara river during migration, Masai-Mara game reserve, Kenya.

Denis-Huot / Aerial view of Wildebeest (Connochaetes taurinus) herd migrating. Masai-Mara game reserve, Kenya.

Hanne & Jens Eriksen / Ortolan bunting (Emberiza hortulana) male perched, during migration, Oman, April.

Hanne & Jens Eriksen / European nightjar (Caprimulgus europaeus) in flight over the ocean, during autumn migration, Oman, October.

Hanne & Jens Eriksen / Northern wheatear (Oenanthe oenanthe) male on rock during migration, Oman, April.

Roger Powell / Migrating flock of Golden plover (Pluvialis apricaria) against a stormy sky arriving in Northumberland. Cresswell, Northumberland, UK. November.

Cyril Ruoso / Flock of Barn swallows (Hirundo rustica) perched on power lines during migration, France. September.

Anup Shah / Wildebeest (Connochaetes taurinus) and Common zebra (Equus quagga) crossing Mara river during migration, Masai Mara NR, Kenya

Anup Shah / Wildebeest juvenile jumping into Mara River, Masai Mara, Kenya

Anup Shah / Common zebra (Equus quagga) crossing river Masai Mara reserve, Kenya

Doug Allan / White / Beluga whale pod {Delphinapterus leucas} migrating through sea ice, Arctic Canada. Aerial

Michel Roggo / European Eel (Anguilla anguilla) juveniles migrating upstream, Rhine River, Switzerland, 1992

Anup Shah / Common zebra {Zebra burchelli} herd massed together on migration, Masai Mara GR, Kenya

Anup Shah / Eastern white-bearded wildebeest herd (Connochaetes taurinus) waiting to cross the Mara River. Masai Mara National Reserve, Kenya, October 2009

Laurie Campbell / Two Atlantic salmon (Salmo salar) acending waterfall to reach spawning beds, Perthshire, Scotland, November

Konrad Wothe / Three Snow Geese (Chen caerulescens atlanticus / Chen caerulescens) in flight, Bosque del Apache, New Mexico, USA, November

Konrad Wothe / Flock of Snow Geese (Chen caerulescens atlanticus / Chen caerulescens) in flight to their winter roosting site, crossing a full moon, Bosque del Apache, New Mexico, USA, November

Denis-Huot / Wildebeest (Connchaetes taurinus) running down bank of the Mara River during migration, Masai Mara, Kenya

Sven Zacek,Sven Zacek / Two bull Moose (Alces alces) sizing each other up during the annual rut, after sunset with migrating geese in flight. Western Estonia, September.

Alex Mustard / A split level photo of group of Sockeye salmon (Oncorhynchus nerka) fighting their way upstream as they migrate back to the river of their birth to spawn, trees showing autumnal colours. Adams River,...

Anup Shah / Eastern white-bearded wildebeest (Connochaetes taurinus) herd running. Masai Mara National Reserve, Kenya. Taken with remote wide angle camera.

Anup Shah / Eastern White-bearded Wildebeest (Connochaetes taurinus) herd crossing the Mara River. Maasai Mara National Reserve, Kenya.