Tony Wu / Zoarchias major eelpout (Zoarchias major) female attempting to dislodge a male from a hole in the reef. Yamaguchi Prefecture, Japan. Pacific Ocean.

Tony Wu / Zoarchias major eelpout (Zoarchias major) female attempting to dislodge a male from a hole in the reef. Yamaguchi Prefecture, Japan. Pacific Ocean.

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

Suzi Eszterhas / African Elephant (Loxodonta africana) pair fighting, Mashatu Game Reserve, Botswana

John Chan / Two male Southern Pacific rattlesnakes (Crotalus oreganus helleri) fighting during mating season. This behaviour is known as a "combat dance", and is used to determine dominance and the right to mate...

SCOTLAND: The Big Picture / Red squirrel (Sciurus vulgaris), two animals fighting, while falling, Scotland, UK, August.

SCOTLAND: The Big Picture / Red squirrel (Sciurus vulgaris), two animals fighting, while falling, Scotland, UK, August.

SCOTLAND: The Big Picture / Black Grouse (Tetrao tetrix), two males fighting on lek , Scotland, UK. April.

SCOTLAND: The Big Picture / Common Buzzards (Buteo buteo) fighting on ground in snow, Scotland, UK, January.January

SCOTLAND: The Big Picture / Grey seals (Halichoerus grypus) bull seal trying to mate with female on Orkney, Scotland, UK, April.

SCOTLAND: The Big Picture / Two adult bull Grey seals (Halichoerus grypus) fighting in the surf on a beach, Scotland, UK. May.

SCOTLAND: The Big Picture / Male bull seal tries to mate with female Grey seals (Halichoerus grypus) on Orkney, Scotland, UK. April.

Terry Whittaker / Grey Heron ( Ardea cinerea) congregating around the fish stalls as city markets are closing, picking up scraps of food. Amsterdam, Netherlands. April.

Terry Whittaker / Red foxes (Vulpes vulpes) play fighting in sand dunes. Netherlands. November.

Terry Whittaker / Red foxes (Vulpes vulpes) play fighting in sand dunes. Netherlands. November.

Terry Whittaker / Red foxes (Vulpes vulpes) play fighting in sand dunes. Netherlands. November.

Marie Read / Crested caracaras (Caracara cheriway), midair aggressive interaction between two for access to perch, Martin Refuge, Rio Grande Valley, Texas, USA, March.

Suzi Eszterhas / Cotton-top tamarin (Saguinus oedipus), two in tree. Northern Colombia.

David Pattyn / Alpine ibex (Capra ibex) adult males fighting on a steep mountain side, Valsavarenche, Gran Paradiso National Park, Aosta Valley, Italy, May

David Pattyn / Alpine Ibex (Capra ibex) males fighting on a steep slope, Valsavarenche, Gran Paradiso national park, Aosta Valley, Italy, May

David Pattyn / Alpine marmot (Marmota marmota) two males fighting, Gran Paradiso national park, aosta Valley, Italy, May

David Pattyn / Alpine ibex (Capra ibex) adult males fighting in alpine landscape, Valsavarenche, Gran Paradiso National Park, Aosta Valley, Italy, May

David Pattyn / Alpine ibex (Capra ibex) adult males fighting in alpine landscape, Valsavarenche, Gran Paradiso National Park, Aosta Valley, Italy, May

David Pattyn / Alpine ibex (Capra ibex) adult males fighting in alpine landscape, Valsavarenche, Gran Paradiso National Park, Aosta Valley, Italy, May

Ernie Janes / Mute swan (Cygnus olor) attacking Canada goose (Branta canadensis) watched by Coots (Fulica atra) Fleet lagoon, Dorset, England, UK, June.

Matthew Maran / Red Fox (Vulpes Vulpes) vixen bearing her teeth to intimidate last year's cub, North London, England, UK, June.

Willi Rolfes/ BIA / Alpine Marmot (Marmota marmota) pair fighting, Hohe Tauern National Park, Austria

Cyril Ruoso / Przewalski's Horse (Equus ferus przewalskii) sub-adult males fighting, Gobi Desert, Mongolia

Cyril Ruoso / Przewalski's Horse (Equus ferus przewalskii) sub-adult males fighting, Gobi Desert, Mongolia

Cyril Ruoso / Przewalski's Horse (Equus ferus przewalskii) sub-adult males fighting, Gobi Desert, Mongolia

Cyril Ruoso / Przewalski's Horse (Equus ferus przewalskii) stallions fighting, Gobi Desert, Mongolia

Jiri Lochman / Perentie monitor lizard (Varanus giganteus) territorial fight, Barrow Island, Western Australia,

Richard Du Toit / Northern Giraffe (Giraffa camelopardalis) males necking, Kgalagadi Transfrontier Park, South Africa

Markus Varesvuo / Arctic tern (Sterna paradisaea) mobbing Grass snake (Natrix natrix) on rocks below. Uto, Western Finland. June.

Markus Varesvuo / Gannet (Morus bassanus), two fighting over fish. Shetland, Scotland, UK. July.

Winfried Wisniewski / Oryx (Oryx gazella) males fighting, Kgalagadi Transfrontier Park, South Africa

John Chan / Pair of California least terns (Sternula antillarum browni) chasing away a rival male during mating, Huntington Beach, California, USA, May.

Jed Weingarten / Wild Wonders of China / Temminck's tragopans (Tragopan temminckii) fighting, Tangjiahe Nature Reserve, Sichuan province, China.

Jed Weingarten / Wild Wonders of China / Temminck's tragopans (Tragopan temminckii) fighting, Tangjiahe Nature Reserve, Sichuan province, China.

Jed Weingarten / Wild Wonders of China / Temminck's tragopans (Tragopan temminckii) fighting, Tangjiahe Nature Reserve, Sichuan province, China.

Jed Weingarten / Wild Wonders of China / Tibetan macaque (Macaca thibetana) approaching camera with bared teeth, Tangjiahe Nature Reserve, Sichuan Province, China

Andy Rouse / Burchell's Zebra (Equus burchelli) stallions fighting, Masai Mara, Kenya

Andy Rouse / Burchell's Zebra (Equus burchelli) stallions fighting, Masai Mara, Kenya

Andy Rouse / Burchell's Zebra (Equus burchelli) stallions fighting, Masai Mara, Kenya

Andy Rouse / Burchell's Zebra (Equus burchelli) stallions fighting, Masai Mara, Kenya

Andy Rouse / Spotted Hyena (Crocuta crocuta) fighting over hippo carcass in water, Masai Mara, Kenya

Andy Rouse / Spotted Hyena (Crocuta crocuta) fighting over hippo carcass in water, Masai Mara, Kenya

Andy Rouse / Masai Giraffe (Giraffa camelopardalis) young males fighting, Masai Mara, Kenya

Andy Rouse / Masai Giraffe (Giraffa camelopardalis) young males fighting, Masai Mara, Kenya

Denis-Huot / Lion (Panthera leo), in conflict with a group of Spotted hyenas (Crocuta crocuta) on a kill at sunrise, Masai-Mara game reserve, Kenya

Denis-Huot / Lion (Panthera leo), in conflict with a group of Spotted hyenas (Crocuta crocuta) on a kill at sunrise, Masai-Mara game reserve, Kenya

Denis-Huot / Cheetah (Acinonyx jubatus), juveniles playing at sunrise, Masai-Mara Game Reserve, Kenya

Staffan Widstrand / Wild Wonders of China / Herd of Pere David's deer / Milu (Elaphurus davidianus), two females fighting on the shore of the Yangtze river, Hubei Tian'ezhou Milu National Nature Reserve, Shishou, Hubei, China.

Alex Hyde / Southern Elephant Seal bull (Mirounga leonina) challenging a rival male. King Haakon Bay, South Georgia. November.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two in fight over mate with another penguin looking on. Atka Bay, Antarctica. May.

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

Remi Masson / Great blue spotted mudskipper (Boleophthalmus pectinirostris) with mouth open in aggression, on mud at low tide. Kyushu Island, Japan. August.

Remi Masson / Great blue spotted mudskipper (Boleophthalmus pectinirostris) in aggressive pose, on mud at low tide. Kyushu Island, Japan. August.

Remi Masson / Great blue spotted mudskipper (Boleophthalmus pectinirostris) with mouth open in aggressive pose, on mud at low tide. Kyushu Island, Japan. August.

Remi Masson / Great blue spotted mudskipper (Boleophthalmus pectinirostris), two males in territorial fight. On mud at low tide, Kyushu Island, Japan. August.

Remi Masson / Great blue spotted mudskipper (Boleophthalmus pectinirostris), two in territorial fight on mudflat. Kyushu Island, Japan. August.

Nick Upton / Three Red fox (Vulpes vulpes) cubs playing near the entrance to their den at dusk, Somerset, England, UK, May.

Guy Edwardes / Mozambique Spitting Cobra (Naja mossambica) about to spit venom. Kruger, South Africa. Controlled conditions.

Guy Edwardes / Mozambique Spitting Cobra (Naja mossambica) spitting venom. Kruger, South Africa. Controlled conditions.

Guy Edwardes / Pair of Zebra (Equus quagga) fighting in Serengeti National Park, Tanzania

Pedro Narra / Coots (Fulica atra) fighting, Sado Estuary, Portugal. April

Pedro Narra / Coot (Fulica atra) two fighting, Sado Estuary. Portugal. April

Karine Aigner / Bengal tiger (Panthera tigris tigris) female discouraging her sub adult cub from coming near. Ranthambore National Park, Rajasthan, India.

Karine Aigner / Bengal tiger (Panthera tigris tigris) mother warding off her subadult cub. Tourist safari trucks in background. Ranthambore National Park, Rajasthan, India.

Fabrice Cahez / Fieldfare (Turdus pilaris) fighting with blackbird (Turdus merula) over apple in winter, Vosges, France, March.

Fabrice Cahez / Wild cat (Felis silvestris) and Red fox (Vulpes vulpes) fighting, Vosges, France, May. Small repro only.

Paul Hobson / Signal crayfish (Pacifastacus leniusculus) displaying aggression with claws up, split level. River Don, Sheffield, England, UK. September 2018.

Paul Hobson / Signal crayfish (Pacifastacus leniusculus) displaying aggression with claws up. River Don, Sheffield, England, UK. September 2018.

Donald M. Jones / American Bison (Bison bison) bulls fighting, National Bison Range, Montana

SCOTLAND: The Big Picture / Siskin (Carduelis spinus) male showing aggression, perched on lichen covered branch. Scotland, UK. May.

Pal Hermansen / Black-legged kittiwake (Rissa tridactyla), two fighting on snow. Finnmark, Norway. March.

Pal Hermansen / Black-legged kittiwake (Rissa tridactyla), two fighting in mid-air. Above nesting cliff, Hornoya, Finnmark, Norway. March.

Pal Hermansen / Black-legged kittiwake (Rissa tridactyla), two fighting in snow. Hornoya, Finnmark, Norway. March.

Pal Hermansen / Stag beetle (Lucanus cervus), two males fighting on lichen covered branch. Oland, Gotland, Sweden. June. 2019 Highly commended in the Magical Nature Contest hosted by Association of Slovenian Nature P...

Loic Poidevin / Mediterranean gulls (Ichthyaetus melanocephalus) fighting, Vendee, France, June

Loic Poidevin / Common terns (Sterna hirundo) pair fighting in flight, Noirmoutier Island, Vendee, France, June.

Christophe Courteau / Mountain gorilla (Gorilla gorilla beringei), two males, silverback fighting a blackback. Volcanoes National Park. Rwanda.

Andy Rouse / White-necked Jacobin hummingbird (Florisuga mellivora) hovering with tail erect to show aggression , Tobago

Ingo Arndt / Guanaco (Lama guanicoe) males fighting, Torres del Paine National Park, Patagonia, Chile

Ingo Arndt / Andean Condor (Vultur gryphus) pair fighting while flying, Torres del Paine National Park, Patagonia, Chile

Shane Gross / Nurse shark (Ginglymostoma cirratum) male biting onto the pectoral fin of a female whilst mating, Eleuthera, Bahamas.

Shane Gross / Nurse shark (Ginglymostoma cirratum) male biting onto the pectoral fin of a female whilst mating, Eleuthera, Bahamas.

Shane Gross / Nurse shark (Ginglymostoma cirratum) two males bite onto the pectoral fins of a larger female while trying to mate with her, Eleuthera, Bahamas

Shane Gross / Nurse shark (Ginglymostoma cirratum) male biting onto the pectoral fin of a female whilst mating, Eleuthera, Bahamas.

Shane Gross / Nurse shark (Ginglymostoma cirratum) male biting onto the pectoral fin of a female whilst mating, Eleuthera, Bahamas.

Shane Gross / Nurse shark (Ginglymostoma cirratum) bites onto a female while mating in the shallows, with another male nearby. Eleuthera, Bahamas. Awarded in underwater category, Wildlife Photographer of the Year 2...

Hermann Brehm / Kestrel (Falco tinnunculus) fighting Hungary, April.

Kristel Richard / Two wild stallions (Equus caballus) fighting, in the Cincar mountains, near Livno, Bosnia and Herzegovina.

Kristel Richard / Two wild stallions (Equus caballus) fighting, in the Cincar mountains, near Livno, Bosnia and Herzegovina.