Michel Poinsignon / Praying mantis (Mantis religiosa) pair on plant facing each other, Lorraine, France, September.

Yva Momatiuk & John Eastcott / Mustang (Equus caballus) young bachelor stallions sniffing each other, Pryor Mountain Wild Horse Range, Montana

Anup Shah / Western chimpanzee (Pan troglodytes verus) juvenile female 'Joya' aged 6 years playing with infant male 'Flanle' aged 3 years, Bossou Forest, Mont Nimba, Guinea. January 2011. Sequence 1 of 2.

XI ZHINONG / Tibetan antelope (Pantholops hodgsoni), two males, Kekexili, Qinghai, Tibetan Plateau, China, December

XI ZHINONG / Blue Sheep (Pseudois nayaur) on hillside, Kekexili, Qinghai, China, January

Jabruson / African Forest elephant (Loxodonta africana cyclotis) two bulls sparring, competition for access to valuable minerals located at certain points within the clearing's water points, Dzanga-Ndoki Nationa...

Andrew Parkinson / Bengal Tigers (Panthera tigris) sub-adults, approximately 17-19 months old, playfighting. Endangered. Bandhavgarh National Park, India. Non-ex. Sequence 1 of 2.

Juan Carlos Munoz / Great Blue Heron (Ardea herodias) pair facing each other. Everglades National Park, Florida, USA, February.

Brent Stephenson / Pair of Snowy Sheathbills (Chionis alba) sitting facing each other on a rock. Port Lockroy, Antarctic Peninsula, Antarctica, January.

Loic Poidevin / Mute Swan (Cygnus olor) and Black Swan (Cygnus atratus) facing each other on water. The Vendeen Marsh, French Atlantic Coast, October.

Theo Allofs / Red Kangaroo (Macropus rufus) males facing each other before fight over female, Sturt National Park, New South Wales, Australia

Theo Allofs / Red Kangaroo (Macropus rufus) males facing each other before fight over female, Sturt National Park, New South Wales, Australia

David Kjaer / Brown Hare (Lepus europaeus) facing each other, standing on hind legs. Wiltshire, UK, June.

Andrew Parkinson / Black guillemot (Cepphus grylle) pair of adults facing each other, Shetland Islands, Scotland, UK, July.

Bernard Castelein / Two Grizzled skipper butterflies (Pyrgus malvae) facing each other on seed head, Brasschaat, Belgium, April

Nature Production / Pintail ducks (Anas acuta) facing each other, interacting, Iwate, Japan, February

Hermann Brehm / Two Great Crested Grebe (Podiceps cristatus) facing each other during courtship display, Bavaria, Germany, March.

Juan Carlos Munoz / Greater black backed gulls (Larus marinus) two standing, facing each other, camouflaged against snow, Lokka lake, Finland, April 2008

Wild Wonders of Europe / Elander / Two Griffon vultures (Gyps fulvus) with wings outstretched facing each other with another moving away, Cebollar, Torla, Aragon, Spain, November 2008

Suzi Eszterhas / Two White rhinoceros {Ceratotherium simum} facing each other, Lewa Conservancy, Kenya

Suzi Eszterhas / Two White rhinoceros {Ceratotherium simum} facing each other, Lewa Conservancy, Kenya

Michael Hutchinson / Black-headed gull (Chroicocephalus ridibundus) in winter plumage, two facing each other on railing, Bristol, UK

Yva Momatiuk & John Eastcott / Mustang (Equus caballus) young bachelor stallions grooming each other, Pryor Mountain Wild Horse Range, Montana

Michael Quinton / Alaska Moose (Alces alces gigas) pair of males confronting each other in the fall, Alaska

Tony Evans / Two Sulphur crested cockatoos head to head, facing each other {Kakatoe galerita} captive

Richard Du Toit / Burchell's Zebra (Equus burchellii) pair facing each other, Rietvlei Nature Reserve, Gauteng, South Africa