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...

Yashpal Rathore / Bengal tiger (Panthera tigris tigris) walking at night, with monsoon clouds and lightning. Kanha National Park, Central India. Dominant male (T29)

Yashpal Rathore / Bengal tiger (Panthera tigris tigris) dominant male (T29) cooling off in a waterhole Kanha National Park, Central India. Camera trap image.

Yashpal Rathore / Bengal tiger (Panthera tigris tigris) dominant male (T29) cooling off in a waterhole Kanha National Park, Central India. Camera trap image.

Yashpal Rathore / Bengal tiger (Panthera tigris tigris) dominant male (T29) and resident female (T27) cooling off in a watering hole Kanha National Park, Central India. Camera trap image.

Yashpal Rathore / Bengal tiger (Panthera tigris tigris) dominant male (T29) and resident female (T27) cooling off in a waterhole Kanha National Park, Central India. Camera trap image.

Yashpal Rathore / Bengal tiger (Panthera tigris tigris) female (T27) acting cautiously as dominant male (T29) approaches watering hole Kanha National Park, Central India. Camera trap image.

Yashpal Rathore / Bengal tiger (Panthera tigris tigris) dominant male (T29) walking on mud dam wall. Kanha National Park, Central India. Camera trap image.

Yashpal Rathore / Bengal tiger (Panthera tigris tigris) dominant male approaching 'Beja pani' waterhole, Kanha National Park, Central India. Camera trap image.

Christophe Courteau / Mountain gorilla (Gorilla beringei beringei), dominant silverback in forest clearing. Volcanoes National Park, Rwanda.

Frederique Olivier / Close-up of a dominant male Southern elephant seal (Mirounga leonina) calling, Macquarie Island, Sub-Antarctic Australia.

Ingo Arndt / Two Northern elephant seal (Mirounga angustirostris) males fighting for dominance, California, USA

Andy Rouse / Great crested grebe (Podiceps cristatus cristatus) courtship dance, Cardiff, UK, March.

Cyril Ruoso / Bonobo (Pan paniscus) male and female copulating, Lola ya Bonobo Sanctuary, Democratic Republic of Congo

Ole Jorgen Liodden / Waved albatross (Phoebastria irrorata) pair in courtship display, Espanola, Galapagos Islands. Critically endangered species.

Suzi Eszterhas / Proboscis Monkey (Nasalis larvatus) dominant male, Sabah, Borneo, Malaysia

David Pattyn / Great crested grebe (Podiceps cristatus) pair performing their 'weed dance' in which they take a vertical position in front of each other and offer plant material to each other. The Netherlands. March...

Markus Varesvuo / Black Grouse (Tetrao tetrix) two males fighting, Liminka, Finland, March

Markus Varesvuo / Black Grouse (Tetrao tetrix) two males fighting, Liminka, Finland, March

Markus Varesvuo / Black Grouse (Tetrao tetrix) two males fighting, Liminka, Finland, March

Ammonite / African lioness (Panthera leo) growling and swatting at a sub-adult male approaching a kill, footage taken at night using thermal camera technology, Masai Mara, Kenya.

Jabruson Motion / Small group of African forest elephants (Loxodonta africana cuclotis) running into forest clearing, trumpeting to dominant male feeding and cooling down in a mineral pool, Dzanga Bai, Dzanga-Ndoki Nat...

Laurent Geslin / Two male urban Red foxes, territorial posture at junction of territories {Vulpes vulpes} London, UK

Laurent Geslin / Two male urban Red foxes, mouths open, one in submissive posture {Vulpes vulpes} London, UK

Laurent Geslin / Two dominant male urban Red foxes fighting on road {Vulpes vulpes} London, UK

Laurent Geslin / Two dominant male urban Red foxes fighting on road, mouths open {Vulpes vulpes} London, UK

Laurent Geslin / Two dominant male urban Red foxes fighting on road {Vulpes vulpes} London, UK

Cyril Ruoso / Eastern Chimpanzee (Pan troglodytes schweinfurthii) , Frodo the dominant male and hunter, eating a Red River Hog (Potamochoerus porcus) piglet with two females begging, Gombe National Park, Tanzania

Denis-Huot,Denis-Huot / Lion (Panthera leo) mating, Masai-Mara Game Reserve, Kenya. Vulnerable species.

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

Christophe Courteau / Mountain Gorilla (Gorilla beringei) dominant male silver back sitting amongst vegetation. 2700 metres above sea level in Volcanoes National Park, Rwanda. short dry season, February

Christophe Courteau / Gelada Baboon (Theropithecus gelada) dominant male threat display, lip curl, Simien NP, Ethiopia, 3000m altitude

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years peering through vegetation, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Re...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged about 32 years scratching his head, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Rep...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) rear view of dominant male Silverback 'Makumba' aged approx 32 years standing on a forest track, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years feeding on sedge grasses in Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Re...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years feeding on rotten wood from a tree while his juvenile son 'Tembo' aged 4 years waits his turn, Bai Ho...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years standing portrait, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republic. D...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years feeding on rotten wood from a tree while female 'Malui' and their juvenile son 'Tembo' aged 4 years s...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years sitting in a forest clearing, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years feeding on rotten wood from a tree while female 'Malui' and their juvenile son 'Tembo' aged 4 years s...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years feeding on rotten wood from a tree while his juvenile son 'Tembo' aged 4 years waits his turn, Bai Ho...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years feeding on sedge grasses in Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Re...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years feeding on sedge grasses in Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Re...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years feeding on sedge grasses in Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Re...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years feeding on sedge grasses in Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Re...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years sitting in a forest clearing, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years walking through Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republic. Dece...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years walking through the forest, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Re...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years drinking from a river while sub-adult female 'Mosoko' aged 8 years crosses bi-pedally, Bai Hokou, Dza...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years drinking from a river watched by sub-adult female 'Mosoko' aged 8 years and juvenile male 'Mobangi' a...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years approaching a river while sub-adult female 'Mosoko' aged 8 years and juvenile male 'Mobangi' aged 5 y...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years sitting portrait, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republic. De...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years feeding on fruit with his son 'Tembo' aged 4 years sitting in the background, Bai Hokou, Dzanga Sangh...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years head and shoulders portrait, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African R...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years climbing down a tree, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republic...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years climbing down a tree, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republic...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) juvenile male 'Tembo' aged 4 years crossing a river bi-pedally while dominant male silverback 'Makumba' aged 32 years and juvenile male 'Mobangi' aged...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years feeding on fruit, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republic. De...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years sitting in a forest clearing, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years feeding on leaves, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republic. D...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years moving through a tree, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republi...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) juvenile males 'Mobangi' aged 5 years and 'Tembo' aged 4 years walking in to a bai with dominant male silverback 'Makumba' aged 32 years drinking in t...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years feeding on sedge grasses in Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Re...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years standing portrait, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republic. D...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years sitting portrait with other behind, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central Af...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years sitting portrait, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republic. De...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years walking bi-pedally across a river, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central Afr...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years sitting by a river in forest interior, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years standing in a bai having just emerged from the forest, Bai Hokou, Dzanga Sangha Special Dense Forest...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years standing at the edge of the forest, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central Af...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years walking at the edge of the forest, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central Afr...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years standing in a bai watched by son 'Tembo' aged 4 years, Bai Hokou, Dzanga Sangha Special Dense Forest...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years drinking from a pool of water in Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central Afric...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years sitting at the edge of the forest, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central Afr...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years sitting at the edge of the forest, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central Afr...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years walking at the edge of the forest, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central Afr...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged about 32 years feeding on fruit, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republ...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years standing at the edge of the forest, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central Af...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years sitting in a tree, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republic. D...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years feeding on sedge grasses in Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Re...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years feeding on sedge grasses in Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Re...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years head and shoulders portrait, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African R...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years sitting portrait, with other gorilla behind, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, C...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) rear view of dominant male silverback 'Makumba' aged 32 years walking along a forest trail, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Cen...

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years resting on his back on the forest floor, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Centr...

Fiona Rogers / Western lowland gorilla (Gorilla gorilla gorilla) dominant male silverback 'Makumba' aged 32 years head and shoulders portrait, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African R...

David Pattyn / Alpine ibex (Capra ibex) adult male chasing two young males away, Gran Paradiso National Park, Italy, July

David Pattyn / Red necked grebe (Podiceps grisegena) approaching a competitor in an attempt to drive him away during the courting season, Danube area, Bulgaria, April

Anup Shah / Western lowland gorilla (Gorilla gorilla gorilla). dominant male silverback 'Makumba' aged 32 years, Bai Hokou, Dzanga Sangha Special Dense Forest Reserve, Central African Republic, December 2011

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

Christophe Courteau / Mountain gorillas (Gorilla beringei) Hirwa group led by the silverback dominant male Munyinya, Volcanoes National Park, Rwanda, elevation 2610 m

Christophe Courteau / Mountain gorilla silverback, male called Munyinya, (Gorilla beringei) with tourist taking photo, part of Hirwa Group, Volcanoes National Park, Rwanda

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

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

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...