Nick Gordon / Silky marmosets {Callithrix humeralifer chrysoleuca} aggression, Amazonia, Brazil

Anup Shah / Juvenile Tawny or African Sea Eagle defending flamingo carcass from Marabou stork {Lepitoptilos crumeniferous}

Anup Shah / African fish eagle {Haliaeetus vocifer} fighting Marabou storks {Leptoptilos crumeniferus} over Lesser flamingo carcass, Lake Nakuru, Kenya.

Richard Du Toit / Burchell's Zebra (Equus burchellii) males fighting, Rietvlei Nature Reserve, Gauteng, South Africa

Richard Du Toit / Burchell's Zebra (Equus burchellii) males fighting, Rietvlei Nature Reserve, Gauteng, South Africa

Paul Hobson / Arctic tern (Sterna paradisaea) two fighting in the air, Scotland, UK July

Denis-Huot / Masai Giraffe (Giraffa camelopardalis tippelskirchi), males fighting. Masai-Mara game reserve, Kenya.

Igor Shpilenok / Male Caucasian turs (Capra caucasica) rutting with Dykh-tau Mountain in the background, Kabardino-Balkarsky Zapovednik / Reserve, Russia, July

Winfried Wisniewski / Masai Giraffe (Giraffa tippelskirchi) males fighting, Masai Mara, Kenya

Anup Shah / Topi (Damaliscus lunatus jimela) two males sparring, with another approaching, Masai Mara National Reserve, Kenya. March

David Pattyn / Siskins (Carduelis spinus) fighting over food. Oisterwijk, The Netherlands, March.

Juan Carlos Munoz / Bearded Vultures (Gypaetus barbatus) juvenile (left) and adult fighting in flight. Simien National Park, Ethiopia, Africa.

Wild Wonders of Europe / Widstrand / Ganado bravo, fighting bull portrait, Ciudad Rodrigo, Salamanca Region, Castilla y Leon, Spain

Mark Carwardine / Amazon river dolphin, pink river dolphin or boto (Inia geoffrensis) Rio Negro, Brazil (Amazon) - two wild animals fighting over fish Threatened species (IUCN Red List)

Floris van Breugel / Two Bull Northern Elephant Seals (Mirounga angustirostris) face off before fighting in the middle of the extensive Piedras Blancas rookery with over 150 seals just in this photo, mostly pregnant or nu...

Ole Jorgen Liodden / Royal Penguin (Eudyptes schlegeli) fighting, Macquarie Island, Sub-Antarctic Australia. November.

Ole Jorgen Liodden / Royal Penguins (Eudyptes schlegeli) fighting, Macquarie Island, Sub-Antarctic Australia. November.

Christophe Courteau / Fighting between a pack of 21 African Wild Dogs {Lycaon pictus} and the dominant female of a clan of Spotted Hyaenas (Crocuta crocuta) Northern Okavango Delta, Botswana

Christophe Courteau / Fighting between a pack of 21 African Wild Dogs {Lycaon pictus} and the dominant female of a clan of Spotted Hyaenas (Crocuta crocuta) Northern Okavango Delta, Botswana

Christophe Courteau / Two African Buffalo {Sincerus caffer} bulls sparring, Okavango Delta, Botswana.

Anup Shah / Mature male gelada (Theropithecus gelada) fighting head-on, upper lip curled back revealing teeth. Simien Mountains National Park, Ethiopia.

David Pattyn / Red foxes (Vulpes vulpes) two fighting, probably over territory, The Netherlands, August

Juan Carlos Munoz / Great Egrets (Ardea alba) territorial fight above nest colony, Everglades National Park, Florida, USA, February.

Juan Carlos Munoz / Great Egrets (Ardea alba) territorial dispute above nest colony, Everglades National Park, Florida, USA, February.

Martin Dohrn / Maricopa harvester ant (Pogonomyrmex maricopa) fighting a different species of ant (Aphaenogaster cockerelli), over territory Arizona, USA

Anup Shah / Eastern White bearded Wildebeest (Connochaetes taurinus) fighting back against attacking African lions (Panthera leo) Masai Mara National Reserve, Kenya, September, sequence 12/12

Andrew Parkinson / Redwings (Turdus iliacus) squabbling over an apple in snow. Derbyshire, UK, February. British Wildlife Photographer of the Year (BWPA) competition 2012, 'Animal Behaviour' category. (Non-ex) Winner of...

Andy Rouse / European hares (Lepus europaeus) boxing, UK

Andy Rouse / European hares (Lepus europaeus) boxing, UK

Paul Williams / Tourists watching two wild Jaguar cubs fight on riverbank whilst third looks on from above (Panthera onca) from boat on river, Pantanal, Pocone, Brazil. No release available.

Andy Rouse / 2020VISION / European Hares (Lepus europaeus) boxing, female on right. Wales, UK, June. Sequence 2 of 2. Did you know? A group of hares is known as a drove.

Andy Rouse / 2020VISION / European Hares (Lepus europaeus) boxing, female on right. Wales, UK, June. Sequence 1 of 2.

Andy Rouse / Agile wallabies (Macropus agilis) sparring and fighting, Bamarru Plains, Northern Territories, Australia

Andy Rouse / Agile wallabies (Macropus agilis) sparring and fighting, Bamarru Plains, Northern Territories, Australia

Charlie Summers / Plains Zebra (Equus quagga) in a dominance fight with dust flying, Lake Magadi, Serengeti, Tanzania.

Edwin Giesbers / Alpine marmots (Marmota marmota) fighting, Hohe Tauern National Park, Austria, July

Carol Walker / Lusitano horse, bull fighter mounted on grey stallion, in this type of bull fighting neither horse nor bull are injured, Portugal, May 2011, model released

Carol Walker / Wild horses / Mustangs, two stallions play fighting, Pryor Mountains, Montana, USA, July 2010

Kim Taylor / Two Siskins (Carduelis spinus) fighting, Surrey, UK, March

Mark Hamblin / 2020VISION / Goldfinches (Carduelis carduelis) squabbling over teasel seeds in winter. Hope Farm RSPB reserve, Cambridgeshire, England, UK, February. Crop of 01390677

Mark Hamblin / 2020VISION / Mountain Hares (Lepus timidus) boxing in winter. Cairngorms National Park, Scotland, UK, January. Did you know? Although they are normally solitary, Mountain hares can gather in groups of up to 20 dur...

Danny Green / 2020VISION / Two European river otters (Lutra lutra) fighting over a fish, Isle of Mull, Inner Hebrides, Scotland, UK, December

Danny Green / 2020VISION / Two European river otters (Lutra lutra) play fighting in the water, Isle of Mull, Inner Hebrides, Scotland, UK, December

Danny Green / 2020VISION / European river otters (Lutra lutra) play fighting amongst seaweed, Isle of Mull, Inner Hebrides, Scotland, UK, December

Colin Varndell / Greenfinches (Carduelis chloris) squabbling in flight, Dorset, UK, February

George Sanker / Bison (Bison bison) two males head to head, Yellowstone NP, Wyoming, USA

Orsolya Haarberg / Two Black grouse (Tetrao tetrix) males displaying at lek, Bergslagen, Sweden, April

Erlend Haarberg / Two Common redpolls (Carduelis flammea) fighting in flight, Norway, March

Erlend Haarberg / Two Arctic terns (Sterna paradisaea) in flight fighting, Iceland, August

Erlend Haarberg / Two Mountain hares (Lepus timidus) fighting, Sor-Trondelag, Norway, April

Erlend Haarberg / Two Mountain hares (Lepus timidus) fighting, Sor-Trondelag, Norway, April

Rolf Nussbaumer / Northern mockingbird (Mimus polyglottos) adult fighting with Golden-fronted Woodpecker (Melanerpes aurifrons) female over Texas Prickly Pear Cactus (Opuntia lindheimeri) Dinero, Lake Corpus Christi, S...

Ben Hall / Red deer (Cervus elaphus) stags fighting at dusk during rutting season, Cheshire, UK October

Eric Dragesco / Two Przewalski's / Takhi Horses (Equus ferus prezewalski) fighting, Hustai Nuru National Park, Mongolia

Carol Walker / Mustang / wild horses, second year cremello colt Claro play fighting with bay, McCullough Peak herd, Wyoming, USA, July 2009

Carol Walker / Mustang / wild horses, two yearling cremello colts Claro and Cremesso playing with a bay, McCullough Peak herd, Wyoming, USA, June 2008

Marie Read / Two Black-capped chickadees (Poecile atricapillus) in mid-air fight by a sunflower, New York, USA, February

Gerrit Vyn / Dall sheep (Ovis dalli) rams head butting, one behaviour by which males establish dominance during the Autumn mating season. Denali National Park, Alaska, USA

Laurie Campbell / Goldfinches (Carduelis carduelis) squabbling near seed feeder in garden, Berwickshire, Scotland, April

Edwin Giesbers / Two Red fox (Vulpes vulpes) cubs, four months, play fighting, The Netherlands, June

Laurie Campbell / Goldfinches (Carduelis carduelis) squabbling near seed feeder, Berwickshire, Scotland, April

Sergey Gorshkov / Ruffs displaying and fighting (Philomachus pugnax) Agapa River, Taimyr Peninsula, Siberia, Russia

Bertie Gregory / 2020VISION / Red deer (Cervus elaphus) stags fighting during rut, Richmond Park, London, England, UK, October. Did you know? Richmond Park deer herds are descended from historic medieval royal hunting stock.

Bertie Gregory / 2020VISION / Red deer (Cervus elaphus) stags fighting during rut, with blocks of flats in the background, Richmond Park, London, England, UK, October

Bertie Gregory / 2020VISION / Red deer (Cervus elaphus) stags fighting during rut, Richmond Park, London, England, UK, October

Markus Varesvuo / Horned / Slavonian grebe (Podiceps auritus) two individuals fighting in water, Finland May

Kristel Richard / During the Festa do Colete Encarnado (Red Waistcoat Festival), a bull running festival, a traditionally dressed 'cavalheiro' delivers the 'banderilla' mounted on his Lusitano stallion in the bullring...

Juan Carlos Munoz / Two White Tailed Sea Eagle (Haliaeetus albicilla) fighting in acrobatic flight as Raven (Corvus corax) looks on. Scandinavia, April. 5th, 2010 Euronatur Wildlife photographer competition.

Juan Carlos Munoz / Two White Tailed Sea Eagle (Haliaeetus albicilla) fighting in acrobatic flight as Raven (Corvus corax) looks on and a Herring Gull (Larus argentus) flies past. Scandinavia, April.

Sven Zacek / Two Black Grouse (Tetrao tetrix) fighting at a lek. Virumaa, Estonia, Europe, April.

Anup Shah / Caracal (Caracal caracal) two six month kittens play fighting, Masai Mara National Reserve, Kenya, August

Anup Shah / Caracal (Caracal caracal) two six month kittens play fighting, Masai Mara National Reserve, Kenya, August

Andy Rouse / Two Common Zebra (Equus quagga) fighting. Masai Mara, Kenya.

Colin Varndell / Male Greenfinches (Carduelis chloris) squabbling in flight. Dorset, UK, March.

Terry Whittaker / 2020VISION / Two Red deer (Cervus elaphus) stags fighting, rutting season, Bushy Park, London, UK, October

Terry Whittaker / 2020VISION / Red deer (Cervus elaphus) stag chasing another during a fight, rutting season, Bushy Park, London, UK, October

Ole Jorgen Liodden / Beisa oryx (Oryx beisa) fighting in rut. Samburu, Kenya, December.

Ole Jorgen Liodden / Galapagos Ghost Crab (Ocypode gaudichaudii) fighting on the beach. Galapagos

Andrew Parkinson / 2020VISION / Marsh harrier (Circus aeruginosus) three sub-adult siblings squabbling in flight in the last rays of evening sunlight, Norfolk, UK, August

Terry Whittaker / 2020VISION / Konik horse (Equus caballus) two stallions fighting, Wicken Fen, Cambridgeshire, UK, June

Terry Whittaker / 2020VISION / Konik horse (Equus caballus) two stallions fighting, Wicken Fen, Cambridgeshire, UK, June

Dave Watts / Eastern grey kangaroo (Macropus giganteus) two males boxing, Australian Capital Territory, Australia, December

Mary McDonald / Common Zebra (Equus quagga) stallions fighting. Naabi Plains, Serengeti National Park, Tanzania.

Mary McDonald / Common Zebra (Equus quagga) stallions fighting. Naabi Plains, Serengeti National Park, Tanzania.

Loic Poidevin / Ruff (Philomachus pugnax) two rival males displaying, fighting, Varanger, Norway, June

Loic Poidevin / Ruff (Philomachus pugnax) two rival males displaying, fighting, Varanger, Norway, June

Mark Hamblin / 2020VISION / Black grouse (Tetrao tetrix) two males displaying and fighting at lek, Cairngorms NP, Grampian, Scotland, UK, April

Mark Hamblin / 2020VISION / Black grouse (Tetrao tetrix) males fighting at lek site, Cairngorms National Park, Grampian, Scotland, UK, April

Mark Hamblin / 2020VISION / Black grouse (Tetrao tetrix) males fighting at lek site, Cairngorms National Park, Grampian, Scotland, UK, April

Mark Hamblin / 2020VISION / Black grouse (Tetrao tetrix) two males fighting at lek site with mountains in the background, Cairngorms National Park, Grampian, Scotland, UK, April. 2020VISION Exhibition. 2020VISION Book Plate.

Andy Rouse / Two Grizzly bears (Ursus arctos horribilis) male (right) and female fighting over salmon, Katmai NP, Alaska, USA, August

Andy Rouse / Two Grizzly bears (Ursus arctos horribilis) male (right) and female fighting over salmon, Katmai NP, Alaska, USA, August

Anup Shah / Adolescent male Lions (Panthera leo) play fighting, Masai Mara National Reserve, Kenya, March

Anup Shah / African Elephant (Loxodonta africana) juveniles play fighting, Masai Mara National Reserve, Kenya, February