Morley Read / Slow motion clip of a group of male Mallards (Anas platyrhynchos) competing violently to mate with a single female, Cornwall, England, UK, May 2018.

Bence Mate / European rabbits (Oryctolagus cuniculus) fighting each other, Kiskunsag National Park, Hungary. June. Winner, General Fauna Category, 2019 Cadiz Photo Nature Competition.

Diane McAllister / Polar bears (Ursus maritimus) fighting in water. Beaufort Sea , Kaktovik Alaska. USA. Highly commended in the Polar Passion category of the Nature's Best Photography Competition 2019.

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.

Gerry Ellis / Chimpanzee (Pan troglodytes) orphans, Larry investigating Daphne's tongue, Ape Action Africa, Mefou Primate Sanctuary, Cameroon

Jami Tarris / Polar Bear (Ursus maritimus) hunting Bearded Seal (Erignathus barbatus) pup, Spitsbergen, Svalbard, Norway

Juergen & Christine Sohns / African Lion (Panthera leo) six week old cubs, Tswalu Game Reserve, South Africa

Juergen & Christine Sohns / Meerkat (Suricata suricatta) pair on alert, Tswalu Game Reserve, South Africa

Juergen & Christine Sohns / Meerkat (Suricata suricatta) pair on alert, Tswalu Game Reserve, South Africa

Juergen & Christine Sohns / Meerkat (Suricata suricatta) pair on alert, Tswalu Game Reserve, South Africa

Juergen & Christine Sohns / Meerkat (Suricata suricatta) pair on alert, Tswalu Game Reserve, South Africa

Anup Shah / Olive Baboon (Papio anubis) male with three month old young, Gombe National Park, Tanzania

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

Sergio Hanquet / Green sea turtle (Chelonia mydas), two viewed from above. Tenerife, Canary Islands.

Danny Green / Polar bear (Ursus maritimus) and two cubs feeding on Whale carcass. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus), male and female approaching each other across snow covered rocky landscape. Svalbard, Norway, April 2019.

Danny Green / Polar bear (Ursus maritimus) male approaching female on snow covered hill top. Svalbard, Norway, April 2019.

Danny Green / Polar bear (Ursus maritimus) male approaching female in rocky area covered in snow. Svalbard, Norway, April 2019.

Danny Green / Arctic fox (Vulpes lagopus), two in snow covered landscape. Svalbard, Norway, April 2019.

Danny Green / Ringed seal (Pusa hispida) and pup resting on ice. Svalbard, Norway. April.

Danny Green / Reindeer (Rangifer tarandus), two standing on ridge in blizzard. Svalbard, Norway. April.

Danny Green / Reindeer (Rangifer tarandus), two play fighting in snow. Svalbard, Norway, April.

Danny Green / Reindeer (Rangifer tarandus), two standing on ridge in snow. Svalbard, Norway, April.

Danny Green / Polar bear (Ursus maritimus) two walking in snowy landscape. Svalbard, Norway, April 2018.

Danny Green / Polar bear (Ursus maritimus) male female pair looking upwards, snow covered hills in background. Svalbard, Norway, April 2018.

Danny Green / Polar bear (Ursus maritimus), two cubs playing, leaping across sea ice, reflected in water. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus), two cubs walking on sea ice. Svalbard, Norway, July.

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

Neil Anderson / Red squirrel (Sciurus vulgaris), two curled up asleep in drey inside nest box. Nest of lichen and Pine needles. Highlands, Scotland, UK.

John Cancalosi / Sonoran desert toad (Incilius alvarius) pair mating, with trail of spawn in water. Arizona, USA.

Alex Mustard / Southern stingray (Dasyatis americana) two swimming over sand bar, under stormy sky. Grand Cayman, Cayman Islands. British West Indies.

Alex Mustard / Dugong (Dugong dugon) male and juvenile Golden trevally (Gnathanodon speciosus) swimming over Seagrass (Halophila stipulacea) meadow. Marsa Nabaa, Marsa Alam, Egypt.

Alex Mustard / Green turtle (Chelonia mydas) resting on sea floor and two juvenile Golden trevally (Gnathanodon speciosus). Marsa El Shouna, Marsa Alam, Egypt.

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

Guy Edwardes / Marbled white (Melanagria galathea), two butterflies on Pyramidal orchid (Anacamptis pyramidalis). Badbury Rings, Wimborne Minster, Dorset, England, UK. June.

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

David Tipling / Common European adder (Vipera berus) two males fighting over a female. Holt, North Norfolk, England, UK. April

David Tipling / Common European adder (Vipera berus) two males fighting over a female, Holt, North Norfolk, England, UK. April

David Tipling / Common European adder (Vipera berus) two males fighting over a female, Holt, North Norfolk, England, UK. April.

Shane Gross / Caribbean reef shark (Carcharhinus perezi), two from below, one close up. Caribbean Sea off Gardens of the Queen National Park, Cuba.

Gary Bell/ Oceanwide / Veined Octopus (Octopus marginatus) predating urchin, Anilao, Philippines

Gary Bell/ Oceanwide / Australian Giant Cuttlefish (Sepia apama) male and female, Whyalla, South Australia, Australia

Gary Bell/ Oceanwide / Australian Giant Cuttlefish (Sepia apama) males fighting over female, Whyalla, South Australia, Australia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning mouth of Tomato Grouper (Cephalopholis sonnerati), Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning mouth of Tomato Grouper (Cephalopholis sonnerati), Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning female Stocky Anthias (Pseudanthias hypselosoma), Tulamben, Bali, Indonesia

Gary Bell/ Oceanwide / Whitemouth Moray (Gymnothorax meleagris) being cleaned by Cleaner Wrasse (Labroides sp) juvenile, Christmas Island, Australia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning Yellow-edged Moray (Gymnothorax flavimarginatus), Tulamben, Bali, Indonesia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning Honeycomb Moray Eel (Gymnothorax favagineus), Tulamben, Bali, Indonesia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning mouth of Goldbelly Cardinalfish (Apogon apogonides), Tulamben, Bali, Indonesia

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.

Theo Bosboom / Wave breaking in front of the two famous sea stacks Risin and Kellingin on the Faroe Islands. March 2018.

Ingo Arndt / Mountain Lion (Puma concolor) hunting Guanaco (Lama guanicoe) male, Torres del Paine National Park, Patagonia, Chile, sequence 3 of 12. Joint winner of the Mammal Behaviour Category of the Wildlife Ph...

Staffan Widstrand / African bush elephant, (Loxodonta africana) two head to head playing, Zimanga Private Nature Reserve, KwaZulu Natal, South Africa

Staffan Widstrand / Southern Giraffe (Giraffa camelopardalis) two, with one in foreground, Zimanga Private Nature Reserve, KwaZulu Natal, South Africa

Heather Angel / Northern white cheeked gibbon (Nomascus leucogenys) female standing in tree with baby aged two weeks. Parents captive bred and released. Wild Elephant Valley / Xishuangbanna, Yunnan Province, China, 2...

Ingo Arndt / Female Puma (Puma concolor) with two cubs aged around four months, Torres del Paine National Park, Patagonia, Chile, July.

Mark Raycroft / Woodland Caribou (Rangifer tarandus caribou) mother nursing calf, Newfoundland, Canada

Matthew Maran / Red fox (Vulpes vulpes) dog interacting with a vixen in an urban garden. North London, UK. June.

Matthew Maran / Red fox (Vulpes vulpes) dog interacting with a vixen in an urban garden. North London, UK. July.

Matthew Maran / Red fox (Vulpes vulpes) cub defending its kill (a large dead Brown rat (Rattus norvegicus)) from another cub, North London, UK. August.

Alex Mustard / Pair of Western clown anemonefish (Amphiprion ocellaris) spawning orange eggs on the rock beneath their Magnificent sea anemone (Heteractis magnifica) home on a coral reef. This photo shows the larger...

Alex Mustard / Two female Common seahorses (Hippocampus kuda) fighting over territory on the seabed. The brief fight was preceeded by a ritualised, synchronised parade. Bitung, North Sulawesi, Indonesia. Lembeh Stra...

Alex Mustard / Reef lizardifsh (Synodus variegatus) at a cleaning station, being cleaned by Holthuis anemone shrimps (Ancylomenes holthuisi). Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

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

Tony Wu / Two male Zoarchias major eelpouts (Zoarchias major) engaged in a mouth-to-mouth confrontation. Yamaguchi Prefecture, Japan, Pacific Ocean.

Alex Mustard / Forster's hawkfish (Paracirrhites forsteri) on a coral reef. Jackson Reef, Tiran, Sinai, Egypt. Strait of Tiran, Gulf of Aqaba, Egypt.

Nick Upton / Two Dark green fritillary butterflies (Argynnis aglaja) and a Narrow-bordered five-spot burnet moth (Zygaena lonicerae) nectaring on a Greater knapweed flower (Centaurea scabiosa) in a chalk grassland...

Oriol Alamany / Snow leopard (Panthera uncia) female (hiding below the rock) with her two juveniles resting in snow, in Spiti Valley, Cold Desert Biosphere Reserve, Himalaya, Himachal Pradesh, India, March

Ernie Janes / Black howler (Alouatta caraya) male and female, captive, occurs in Brazil and Paraguay. With digitally added leaf pattern.

Suzi Eszterhas / Leopard (Panthera pardus) mother and eight-month-old cub, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) six-week-old cub nursing, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) six-week-old cubs playing, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) six-week-old cub nuzzling mother, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) mother playing with her six-week-old cub, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) five-week-old cub, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) five-week-old cub, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) five-week-old cub playing with mother's tail, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) five-week-old cub playing with mother's tail, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) mother and five-week-old cub, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) mother grooming five-week-old cub, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) five-week-old cub playing with mother, Jao Reserve, Botswana

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

John Chan / Crenulated fiddler crab (Uca crenulata) waving its major claw at another crab, part of a courtship display, Southern California, USA, June.

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 / Sally lightfoot crabs (Grapsus grapsus) on the beach at Puerto Egas, Santiago Island, Galapagos, May.

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.

Espen Bergersen / Humpback whales (Megaptera novaeangliae) showing tail fluke when they dive. Kvanangen, Troms, Norway. December

Espen Bergersen / Killer whales / orcas (Orcinus orca) and boat in background. Kvanangen, Troms, Norway. November

Espen Bergersen / Killer whales / orcas (Orcinus orca) two spyhopping. Kvaloya, Troms, Norway October

Espen Bergersen / Killer whales / orcas (Orcinus orca) two spyhopping. Kvaloya, Troms, Norway October

Andy Rouse / Sally lightfoot crab, (Grapsus grapsus), feeding on marine iguana parasites and dead skin, Galapagos