Winter has begun and with less solar energy the northern hemisphere freezes, life is at its hardest; as the planet starts its incredible journey around the sun, Earth's northern pole tilts away from the warmth and light.

Spring is a season of opportunity - the great melt begins, and new life erupts. But for those animal families in the southern hemisphere conditions are getting harsher. Days grow shorter and animals must prepare for tougher times to come.

Summer is the season of extremes. By June, the top of the planet is 24 hours of sunlight, while the south is frozen in darkness. Whilst for the northern hemisphere this is a season of plenty, much of the south will face famine, fire and torrential rain.

Autumn is the season of change. It offers a chance to begin again or take a new path in life. As the year draws to a close and winter returns, preparedness is key. For those that succeed, their place in the next year's circle of life is safe.

In the time it takes us to complete our annual orbit around the sun, a newly hatched penguin chick grows a fluffy coat and swims past killer whales to leave home. A panda cub's patience is tested with Mum's never-ending meal.

Scientists, community members and conservationists uncover new behavior, use pioneering and inventive techniques and put their lives on the line to protect the animals that roam the earth.