Donald M. Jones / Dall's Sheep (Ovis dalli) rams posturing, central Alaska

Donald M. Jones / Dall's Sheep (Ovis dalli) rams posturing, central Alaska

Nick Garbutt / Adult male Hippopotamus (Hippopotamus amphibius) posturing in agressive 'yawn' behaviour, Luangwa River, South Luangwa National Park, Zambia, November

Nick Garbutt / Adult male Hippopotamuses (Hippopotamus amphibius) posturing in aggressive 'yawn' behaviour, Luangwa River, South Luangwa National Park, Zambia, November. Digital composite (two frames stitched togeth...

Yva Momatiuk & John Eastcott / Mustang (Equus caballus) harem stallions posturing as prelude to fight, Montana

Roger Powell / Pair of Common eiders (Somateria mollissima). Male preening with female circling and posturing for copulation. Amble Harbour, Northumberland, England, UK, March

Donald M. Jones / Elk (Cervus elaphus) young bulls play-fighting, western Canada

Donald M. Jones / Elk (Cervus elaphus) young bulls play-fighting, western Canada

Donald M. Jones / Dall's Sheep (Ovis dalli) rams posturing, central Alaska

Donald M. Jones / Dall's Sheep (Ovis dalli) rams posturing, central Alaska

Donald M. Jones / Dall's Sheep (Ovis dalli) rams posturing, central Alaska

Andy Trowbridge / Male Chamois (Rupicapra rupicapra) posturing with hair raised along its back. Lauson's Valley, Gran Paradiso National Park, Italy, September.

Andy Trowbridge / Male Chamois (Rupicapra rupicapra) posturing with hair raised along its back. Lauson's Valley, Gran Paradiso National Park, Italy, September.

Markus Varesvuo / Wallcreeper (Tichodroma muraria) posturing against rocks, Spain

Markus Varesvuo / Wallcreeper (Tichodroma muraria) posturing, against rocks, Spain

Donald M. Jones / Bighorn Sheep (Ovis canadensis) rams posturing during rut, Montana

Cyril Ruoso / Golden Snub-nosed Monkey (Rhinopithecus roxellana) males fighting during mating season, Qinling Mountains, China

Hiroya Minakuchi / Steller's Sea Lion (Eumetopias jubatus) female posturing at sub-adult male, Alaska

Charlie Summers / Tawny eagle (Aquila rapax) advancing on another unseen Eagle using an aggressive posture. This is the light phase of the Tawny eagle. Ngorongoro Crater, Tanzania, February

Sergey Gorshkov / Ruff displaying (Philomachus pugnax) Agapa River, Taimyr Peninsula, Siberia, Russia

Fabrice Cahez / Two Rooks (Corvus frugilegus) posturing on snow. Vosges, France, January.

Carol Walker / Wild horses / mustangs, two stallions posturing, Pryor Mountains, Montana, USA, June

Carol Walker / Wild horse / mustang, pinto stallion posturing, McCullough Peaks Herd Area, northern Wyoming, USA, June

Carol Walker / Wild Horse / mustang, stallion posturing, stamping, Pryor Mountains, Montana, USA, June

Charlie Summers / Franklin's Gulls (Leucophaeus pipixcan) posturing as they communicate. West Beach, Gulf Shores, Alabama, April.

Charlie Summers / Wild Horse (Equus caballus) stallion dominance posturing in the fog. Montana, USA, June.

Charlie Summers / Bull Elk (Cervus canadensis) standing, posturing in Madison river, Yellowstone NP, Montana, USA

Sergey Gorshkov / Steller's Sea Eagle (Haliaeetus pelagicus) and Golden Eagle (Aquila chrysaetos) posturing and fighting over food, Kamchatka, Russia

Sergey Gorshkov / Steller's Sea Eagle (Haliaeetus pelagicus) pair posturing and fighting over food, Kamchatka, Russia

Sergey Gorshkov / Steller's Sea Eagle (Haliaeetus pelagicus) and Golden Eagle (Aquila chrysaetos) posturing and fighting over food, Kamchatka, Russia

Sergey Gorshkov / Brown Bear (Ursus arctos) pair posturing at each other along river, Kamchatka, Russia

Andy Rouse / King penguin (Aptenodytes patagonicus) posturing / vocalising on beach, Falkland Islands

Andy Rouse / King penguin (Aptenodytes patagonicus) posturing / vocalising on beach, Falkland Islands

GEORGETTE DOUWMA / Giant cuttlefish (Sepia apama) two breeding males posturing. Spencer Gulf, Whyalla, South Australia.

Yva Momatiuk & John Eastcott / Guanaco (Lama guanicoe) female posturing, Torres del Paine National Park, Chile

GEORGETTE DOUWMA / Giant cuttlefish (Sepia apama) breeding males posturing. Spencer Gulf, Whyalla, South Australia

Carol Walker / Wild horses / mustangs, two stallions posturing, Pryor Mountains, Montana, USA

Sergey Gorshkov / Steller's Sea Eagle (Haliaeetus pelagicus) posturing to make itself appear larger, Kamchatka, Russia

Sergey Gorshkov / Steller's Sea Eagle (Haliaeetus pelagicus) posturing to make itself appear larger, Kamchatka, Russia

Sergey Gorshkov / Steller's Sea Eagle (Haliaeetus pelagicus) posturing to make itself appear larger, trying to intimidate other adult, Kamchatka, Russia

Sergey Gorshkov / Steller's Sea Eagle (Haliaeetus pelagicus) posturing to make itself appear larger, Kamchatka, Russia

Yva Momatiuk & John Eastcott / Sandhill Crane (Grus canadensis) pair posturing and dancing prior to departure for nesting grounds up north, spring, Bosque del Apache National Wildlife Refuge, New Mexico

Yva Momatiuk & John Eastcott / Sandhill Crane (Grus canadensis) pair posturing and dancing prior to departure for northern nesting grounds, spring, Bosque del Apache National Wildlife Refuge, New Mexico

Yva Momatiuk & John Eastcott / Mustang (Equus caballus) stallions posturing and interacting on winter range, Wyoming

Yva Momatiuk & John Eastcott / Mustang (Equus caballus) studs posturing during breeding season, Montana

Tui De Roy / Vicuna (Vicugna vicugna) wild Andean camelid, aggressive posturing, Pampa Galeras Nature Reserve, Peru

Suzi Eszterhas / Clay-colored Thrush (Turdus grayi) fighting with Great Kiskadee (Pitangus sulphuratus), northern Costa Rica

Carol Walker / A wild black curly stallion bowing his head, posturing at another stallion, Salt Wells Creek, Wyoming, USA. May.

Carol Walker / Wild curly stallion posturing, portrait, Salt Wells Creek, Wyoming, USA. June.

Jack Dykinga / Three Roosevelt elk (Cervus canadensis roosevelti) bulls jostling and posturing for dominance, Dean Creek wildlife viewing area, Umpqua River basin, Oregon, USA. July.