Stefan Christmann / Emperor penguin (Aptenodytes forsteri) two adults brooding chicks age 5 weeks, Antarctica. Highly commended in the Polar Passion Category of the Nature's Best Photography Awards 2019.

Martin Willis / Splendid Fairywren (Malurus splendens) female and male, Queensland, Australia

Martin Willis / Rainbow Lorikeet (Trichoglossus haematodus) pair preening during courtship, Magnetic Island, Queensland, Australia

Martin Willis / Budgerigar (Melopsittacus undulatus) father with begging chick at nest cavity, Queensland, Australia

Nick Garbutt / King penguin (Aptenodytes patagonicus), two sleeping on snow. Grytviken, South Georgia. March.

Oscar Dewhurst / Mute swan (Cygnus olor), two cygnets sheltering under parent's wing. Richmond Park, London, England, UK. April.

Claudio Contreras / California condor (Gymnogyps californianus), two peched in tree, adult and juvenile. California condor recovery program, Sierra de San Pedro Martir National Park, Baja California Peninsula, Mexico.

Doug Gimesy / Little blue penguin (Eudyptula minor), two standing on rocks at night, silhouetted against Melbourne city lights. St Kilda breakwater, Victoria, Australia. December 2016. COP26 Countdown Photo Competi...

Loic Poidevin / Eurasian bullfinch (Pyrrhula pyrrhula) male on a branch feeding on Rowan (Sorbus aucuparia) berries, Leon, Spain, February.

John Chan / Great horned owl (Bubo virginianus) chicks stretching and flapping their wings, Southern California, USA, May.

John Chan / Peregrine falcon (Falco peregrinus) plucking Dowitcher (Limnodromus) prey, Southern California, USA.

David Woodfall / Two Little terns (Sterna albifrons) at the nest amongst Black oats (Avena strigosa) growing on shell rich sands Machair, North Uist, Scotland, UK, June.

John Shaw / James' flamingo / Puna flamingo (Phoenicoparrus jamesi). Lago Colorado, Bolivia. March.

John Shaw / Black-browed albatross pair (Thalassarche melanophris) mutual grooming during copulation. New Island, Falkland Islands, November.

Jack Dykinga / Burrowing owls (Athene cunicularia) one moving its head - with blurred motion. Marana, Arizona, USA, November.

Wim van den Heever / King penguins (Aptenodytes patagonicus) at sunrise. Two males and a female, with the males fighting for the attention of the female. Falklands Islands. 2018 Wildlife Photographer of the Year LUMIX Peo...

Terry Whittaker / Mandarin duck (Aix galericulata) male female pair, Reddish Vale Country Park, Greater Manchester, UK. December

Marie Read / Western Grebe (Aechmorphus occidentalis), pair during 'rushing' courtship display in which they run across water's surface in synchrony, near Escondido, California, USA, January.

Marie Read / Canada geese (Branta canadensis) two during territorial fight in early spring, Ithaca. New York, USA

Marie Read / Black-necked stilts (Himantopus mexicanus) pair performing post-copulatory display (as copulation ends, the male slides off the female leaving his wings draped over her and crossing his bill with hers...

Marie Read / Common loons (Gavia immer), two adults and chick swimming on a misty lake in early morning, Michigan, USA. June.

Marie Read / Sandhill cranes (Grus canadensis) (Florida race), adult with two small chicks crossing highway, Kissimmee, Florida, USA, March.

Marie Read / Arctic terns (Sterna paradisaea), two in flight over nesting colony in field of buttercups (Ranunculus sp.), Keflavik, Iceland. Digital canvas expansion.

Marie Read / American oystercatcher (Haematopus palliatus) adult feeding chick, Long Island, New York, USA. June.

Marie Read / American avocets (Recurvirostra americana) two during aggressive (territorial) encounter, Bear River Migratory Bird Refuge, Utah, USA, May.

Alan Murphy/ BIA / Northern Caracara (Caracara cheriway) pair fighting, Texas

Alan Murphy/ BIA / Belted Kingfisher (Megaceryle alcyon) fishing, Texas

Alan Murphy/ BIA / Baltimore Oriole (Icterus galbula) males fighting, Texas

Alan Murphy/ BIA / Baltimore Oriole (Icterus galbula) males fighting, Texas

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) two adults with chicks, age 9-12 weeks, Atka Bay, Queen Maud Land, Antarctica. October.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) two adults with chicks,Atka Bay, Queen Maud Land, Antarctica. October.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) Atka Bay, Queen Maud Land, Antarctica. October.

Stefan Christmann / Adelie penguin (Pygoscelis adeliae) nesting pair, Atka Bay, Queen Maud Land, Antarctica, December.

David Gallan / Male Satin bowerbird (Ptilonorhynchus violaceus) courting female on suburban street verge, bower filled with blue plastic, Australia, October 2018.

Markus Varesvuo / Jay (Garrulus glandarius), two fighting in mid-air with another observing. Norway. October.

Markus Varesvuo / Jay (Garrulus glandarius), two fighting in mid-air with another observing. Norway. October.

George Sanker / Arctic tern (Sterna paradisaea), two fighting in mid-air. Machias Seal Island, New Brunswick / Maine, Canada / USA. July.

Nick Upton / Pair of White storks (Ciconia ciconia) mating on their nest, Knepp Castle Estate, Sussex, England, UK, April. This is the first recorded instance of White storks nesting in the UK for several hundreds...

Nick Upton / Pair of White storks (Ciconia ciconia) arranging nest material on their nest, Knepp Castle Estate, Sussex, England, UK, April. This is the first recorded instance of White storks nesting in the UK for...

Nick Upton / Pair of White storks (Ciconia ciconia) arranging nest material on their nest, Knepp Castle Estate, Sussex, England, UK, April. This is the first recorded instance of White storks nesting in the UK for...

John Chan / Male California least tern (Sternula antillarum browni) presenting fish offering to female during mating, Huntington Beach, California, USA, May.

John Chan / Western gulls (Larus occidentalis) attacking an Elegant tern (Thalasseus elegans) with a broken wing, Southern California, USA, April.

John Chan / Western gull (Larus occidentalis) feeding on a California two-spot octopus (Octopus bimaculoides) on a mudflat at low tide, Southern California, USA, November.

Nick Upton / White stork (Ciconia ciconia) pair mating on their nest at sunset, Knepp estate, Sussex, UK, April 2019. This is the first recorded instance of White storks nesting in the UK for several hundreds of y...

Nick Upton / White stork (Ciconia ciconia) pair performing an up-down display with bill clattering on their nest in an Oak tree, Knepp estate, Sussex, UK, April 2019. This is the first recorded instance of White s...

Nick Upton / White stork (Ciconia ciconia) male landing with nest material and joining his mate on their nest in an Oak tree at sunset, Knepp estate, Sussex, UK, April 2019. This is the first recorded instance of...

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two males, one brooding young chick, the other incubating hatching egg. Atka Bay, Antarctica. August. Series 4/4.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two males, one brooding young chick, the other incubating hatching egg. Atka Bay, Antarctica. August. Series 3/4.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two males, one brooding young chick, the other incubating hatching egg. Atka Bay, Antarctica. August. Series 2/4.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two males, one brooding young chick, the other incubating hatching egg. Atka Bay, Antarctica. August. Series 1/4.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) pair transferring recently laid egg from female to male. Atka Bay, Antarctica. June.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) pair with recently laid egg, on sea ice. Atka Bay, Antarctica. May.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), pair mating. Atka Bay, Antarctica. May.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) pair practising incubating with a snowball. Atka Bay, Antarctica. May.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) pair practising incubating with a snowball. Atka Bay, Antarctica. May. Winner of the Polar Passion Category of the Nature's Best Photography Competition 2019.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) pair in courtship, on sea ice. Atka Bay, Antarctica. May.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) pair, female laying egg. Atka Bay, Antarctica. June.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), pair transferring recently laid egg from female to male. Atka Bay, Antarctica. June. Sequence 2/2.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) pair mating. Atka Bay, Antarctica. May. Sequence 3/4.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) pair mating on sea ice. Atka Bay, Antarctica. May.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) chicks aged 20-24 weeks stretching wings, in moult whilst parents fish at sea. Atka Bay, Antarctica. January.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two adults brooding chicks. Atka Bay, Antarctica. September.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two adults brooding chicks. One chick exhibiting aggression towards other. Atka Bay, Antarctica. September.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two adults with chicks aged six to eight weeks. Atka Bay, Antarctica. September.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two chicks aged six to eight weeks brooding on parents' feet. Atka Bay, Antarctica. September.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two chicks aged six to eight weeks brooding on parents' feet, one vocalising. Atka Bay, Antarctica. September.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) adult brooding chick with two additional chicks seeking protection while parents are at sea. Atka Bay, Antarctica. September.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two chicks aged six to eight weeks huddling together. Atka Bay, Antarctica. September.

Sven Zacek / Ural owl (Strix uralensis) female on nest, male landing with twig in beak. Tartumaa, Southern Estonia. April.

Sven Zacek / Ural owl (Strix uralensis) male presenting prey to nesting mate. Tartumaa, Southern Estonia. April.

Sven Zacek / Ural owl (Strix uralensis) female feeding at nest on rodent prey presented by mate. Tartumaa, Southern Estonia. April.

Donald M. Jones / American Avocet (Recurvirostra americana) pair courting, Montana

Agustin Esmoris / American Oystercatcher (Haematopus palliatus) parent with chick, Chubut, Argentina

Brian Bevan / Juvenile Green woodpecker (Picus viridis) leaving nest hole, shot looking up trunk, Bedfordshire, England, UK, June.

Tim Fitzharris / Ruby-throated Hummingbird (Archilochus colubris) females feeding on flower nectar, Texas

Tim Fitzharris / Ruby-throated Hummingbird (Archilochus colubris) female and Bumblebee (Bombus sp) flying, Arkansas

Steven David Miller / Red-collared lorikeet (Trichoglossus rubritorquis) pair examining hole in Eucalyptus as a potential nesting hollow. Katherine, Northern Territory, Australia.

Steven David Miller / Great bowerbird (Chlamydera nuchalis), male showing off treasures whilst female inspects bower. Lake Argyle, Kununurra, Western Australia.

Tui De Roy / Flightless cormorant (Phalacrocorax harrisi), two on rock. Bird drying wings in foreground with other sitting on nest in background. Cape Douglas, Fernandina Island, Galapagos.

Tui De Roy / Blue-footed booby (Sula nebouxii), pair in courtship display. Punta Pitt, San Cristobal Island, Galapagos. April 2017.

Tui De Roy / Red-footed booby (Sula sula), pair nest building in tree. Darwin Bay, Genovesa Island, Galapagos.

Graeme Guy/ BIA / Blue-throated Bee-eater (Merops viridis) pair, Penang, Malaysia

Glenn Bartley/ BIA / Moustached Turca (Pteroptochos megapodius) pair, Andes, Chile

Jack Dykinga / Burrowing owl (Athene cunicularia), two huddled together. Marana, Pima County, Arizona, USA.

Philippe Clement / Two Atlantic puffins (Fratercula arctica) in breeding plumage on cliff top, Sumburgh Head, Shetland Islands, Scotland, UK, June.

Philippe Clement / Northern gannets (Morus bassanus) sitting on nests made with plastic, Hermaness NNR, Unst, Shetland Islands, Scotland, UK, May.

Philippe Clement / Great cormorant (Phalacrocorax carbo) bringing twig to nest in breeding colony, Belgium, March.

Dave Bevan / Slow motion clip of a pair of Common swifts (Apus apus) approaching and entering a nest hole in limestone cliff, Norfolk, England, UK, May.

Sandesh Kadur / Wide angle shot of a pair of Blue footed boobies (Sula nebouxii) displaying, Galapagos Islands, Ecuador.

Sandesh Kadur / Pair of Waved albatrosses (Phoebastria irrorata) displaying, tapping beaks, Galapagos Islands, Ecuador.

David Allemand / Two Snow geese (Anser caerulescens) during migration, with dark clouds against the sun, Quebec, Canada, October.

David Perpinan / Two Hyacinth macaws (Anodorynchus hyacinthus) in a tree, Pantanal, Mato Grosso do Sul, Brazil.

David Perpinan / Close-up of a carer feeding a Blue fronted amazon (Amazona aestiva), confiscated from illegal wildlife trade, Brazil.

Konrad Wothe / Pair of European nuthatches (Sitta europaea) mating, Bavaria, Germany, April.

John Chan / Male California Least Tern (Sternula antillarum browni) courting a female, presenting a fish before chasing off another male, Huntington Beach, California, USA, May.