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.