Wim van den Heever / Vervet Monkey (Chlorocebus pygerythrus) baby jumping between branches, photographed mid air. Okavango Delta Botswana.

Sven Zacek / Ural owl (Strix uralensis) chick trying to climb an aspen tree with its beak, talons and wings, Southern Estonia. June.

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

Cyril Ruoso / Verreaux's sifaka (Propithecus verreauxi) two resting Berenty, Madagascar.

Espen Bergersen / Atlantic puffin (Fratercula arctica) two fighting in snow, Hornoya bird cliff, Finnmark, Norway. March.

Danny Green / Japanese cranes (Grus japonensis) displaying in snow, Hokkaido, Japan, February

Andy Rouse / Bengal tiger (Panthera tigris tigris) 11 month cubs play fighting, Ranthambhore National Park, India.

Andy Rouse / Bengal tiger (Panthera tigris tigris) 11 month cubs play fighting, Ranthambhore National Park, India.

Denis-Huot / African elephant (Loxodonta africana) having a mud bath at a water hole, Tsavo East National Park, Kenya. August.

Andy Rouse / Mountain Gorilla (Gorilla beringei) adult playing with an infant. Rwanda, Africa

Mark Taylor / Two ginger kittens lying on their sides.

Mark Taylor / Black kitten, 7 weeks, rolling on its back.