5 Animals that learn survival skills through play

The polar bears' annual autumn gathering in Churchill, northern Canada, provides an ideal opportunity for play-fighting. After spending summer in the cool of the forest, the bears in this region head for the sea, arriving hungry and tetchy on the shores of Hudson Bay around Churchill. 

While they wait for the ice to form so they can go hunting for seals, the young males bide their time with mock fights. These practice bouts are a useful rehearsal for the more bloody battles that occur during the breeding season. As cubs, play-fighting in the Arctic snow will have helped to develop the rapid reflexes they need to capture their prey. 

Lion cubs goad each other into mock fights from an early age. They even target their parents, attacking their black-tipped tails. These play-fights are vital rehearsals for adult life as a top predator. 

Mock wrestling matches prepare male cubs for the time when they will have to fight other lions to win control of a pride. Cubs practice catching prey by stalking and chasing each other, swatting at legs to bring an adversary down, or grabbing its rump. 

An Arctic tern chick hatches from its egg and is immediately alert to the positions of the sun, moon and stars in the sky. Within six weeks of hatching, it is ready to leave its nesting site in the Arctic circle and migrate to the Southern Hemisphere. It uses the sun, moon and stars to navigate, as well as the earth's geomagnetic field, as it flies to the opposite end of the world and then home again to the same spot. 

Before the bird migrates for the first time it explores the countryside surrounding its nest site to memorize landmarks. When a juvenile bird reaches Antarctica it may spend up to three years circling the Southern Ocean and its islands before returning north. 

Foals, fawns, lambs, calves and kids frequently explode into life, prancing, leaping, and running about for no apparent reason. These exaggerated movements are not simply for fun. They are thought to be a way of exercising growing muscles and ensuring that nerves and muscles are working in harmony. 

Although they are no longer common prey, horses, deer, sheep, cattle and goats still practise these anti-predator manoeuvres. Gambling and frisking are forms of play that help to tone up their bodies. 

Along South America's Patagonian coast killer whales ride in on the surf and pluck sea lions right off the beach. They then struggle back to sea on the next wave. Youngsters learn the behaviour from older killer whales, perfecting their skills at special practice beaches. 

Having caught their prey, the adults "play" with it, like a cat playing with a mouse, propelling it high into the air. Elsewhere, killer whales play objects in the water. Off the Namibian coast of south-west Africa, they harass jackass penguins and Cape cormorants, grabbing birds in their mouths and then releasing them. 

The Patagonian killer whales tend to beach where the sand or shingle shelves steeply and there is less chance of ending up high and dry. On the Crozet Islands in the southern Indian Ocean, where the beaches have a lower gradient, a row of adults and youngsters will race forwards and beach together to catch elephant seals. 

Parents and "aunties" help any young whale that should become stuck by nudging it back into deeper water.