Two giant panda cubs aged five months playing in a breeding centre, Chengdu, China.

Two male Eastern grey kangaroos (Macropus giganteus) play fighting and hopping away, Australia.

European wildcat kitten playing with its mother's tail, Bavarian Forest National Park, Germany, May

Two male African forest elephants play fighting at a mineral hole, Dzanga-Ndoki National Park, Centr

Two hares boxing in a snow covered field

Female Polar bear grooming, with two cubs playing nearby, Canada.

Close-up of a wild boar (Sus scrofa) approaching a remote camera and knocking it over, UK

Hippopotamus dung spreading with tail, filmed at night using thermal camera, Masai Mara, Kenya.

Two juvenile mountain gorillas sliding down a tree trunk, knocking camera over, Congo

European brown bear cub (Ursus arctos arctos) playing at den entrance in the snow in winter, Germany

Juvenile Red fox playing with slipper in an allotment, London, England, UK, August.

Rhesus macaque mutual grooming, Swayambhunath Temple, Kathmandu, Nepal, 2019.

Grizzly bear cub waking up, Katmai National Park, Alaska, USA,

African forest elephant mother and calf in waterhole, Central African Republic.

Red fox vixen with four suckling cubs in an allotment, one jumping over her back

Northern sea otter sleeping, with paws over eyes, Kachemak Bay, Alaska, USA.

Close-up of a Guanaco feeding, Torres del Paine National Park, Patagonia, Chile, December.

Two Black-bellied hamsters (Cricetus cricetus) fighting, Vienna, Austria, October.

Two Lynx kittens play fighting in front of den entrance, Bavarian Forest National Park, Germany, Oct

Eurasian beaver scratching before jumping into the water, alarmed, Ceredigion, Wales, UK, July.

Bank vole (Myodes glareolus) feeding from a bird feeder alongside a coal tit and blue tit, UK

Eastern grey squirrel entering top of a bird feeder, struggling to get out again, Wales, UK

Brown hares (Lepus europaeus) boxing, Bedfordshire, England

Mountain gorilla pulling lens component off camera

Mountain gorillas captivated by reflection in camera lens

Red squirrel (Sciurus vulgaris) leaping between Scots pine tree, lands on camera, Scotland

Female harp seal surfacing at breathing hole looking at her pup, Canada.

Giant panda cub aged five months stuck after climbing a tree, Chengdu, China

Cute grey seal pup rubbing its head and yawning

Northern tamandua climbing down and falling out of tree, showing use of partially prehensile tail

Giant panda cub aged five months falling asleep in a tree in a breeding centre, Chengdu, China

Long-tailed macaques grooming, with baby playing nearby, Bako NP, Sarawak, Borneo, Malaysia

Female European otter grooming her cub on a rock, with the cub falling into the water, Scotland

Family of African elephants bathing at a waterhole, Tsavo National Park, Kenya

Polar bear playing with ship's mooring rope, Svalbard, Norway

Male Mountain gorilla looking at camera with a juvenile behind him, Virunga National Park, DRC

European brown bear cub playing at den entrance in the snow, Bavarian Forest NP, Germany

Bengal tiger cub playing in a waterhole, Ranthambore National Park, Rajasthan, India

Arctic fox pups playing near their den, Dovrefjell-Sunndalsfjella National Park, Norway

Close-up of a Giraffe chewing, Serengeti National Park, Tanzania

Grey-headed flying-fox defecating by hanging from thumbs the 'right way up', Victoria, Australia