Danny Green / Reindeer (Rangifer tarandus), two play fighting in snow. Svalbard, Norway, April.

Ann & Steve Toon / African elephants (Loxodonta africana) herd silhouetted at sunset. Chobe National Park, Botswana.

Paul Hobson / Red fox (Vulpes vulpes), two cubs play fighting. Sheffield, England, UK. May.

Agustin Esmoris / Southern Elephant Seal (Mirounga leonina) male calling and bleeding after fight, Puerto Madryn, Argentina

Dietmar Nill / Two European hares (Lepus europaeus) boxing in a snow covered field, Germany, March.

SCOTLAND: The Big Picture / European river otter (Lutra lutra) cubs play fighting, Shetland, Scotland, UK, May.

Bence Mate / African wild dogs (Lycaon pictus) play fighting, Mkuze, South Africa

Anup Shah / Southern plains grey langur / Hanuman langur (Semnopithecus dussumieri) juveniles playing . Jodhpur, Rajasthan, India. March.

Anup Shah / Southern plains grey langur / Hanuman langur (Semnopithecus dussumieri) juveniles playing. Jodhpur, Rajasthan, India. March.

Alex Mustard / Galapagos sea lions (Zalophus wollebaeki) young playing in shallow water. Floreana Island, Galapagos Islands, Ecuador. East Pacific Ocean

Yukihiro Fukuda / Japanese macaque (Macaca fuscata fuscata) rare white furred baby playing with another baby. Jigokudani Valley, Nagano Prefecture, Japan. June.

Krijn Trimbos / Great crested grebe (Podiceps cristatus) two in territorial fight, The Netherlands, March.