Spring arrives in the polar regions, and the sun appears after an absence of five months; warmth and life return to these magical ice worlds - the greatest seasonal transformation on our planet is underway. Male Adelie penguins arrive in Antarctica to build their nests - it takes a good property to attract the best mates and the males will stop at nothing to better their rivals! But these early birds face the fiercest storms on the planet. In the Arctic, a polar bear mother is hunting with her cubs. Inland, the frozen rivers start to break up and billions of tons of ice are swept downstream in the greatest of polar spectacles. This melt-water fertilizes the Arctic Ocean, feeding vast shoals of Arctic cod and narwhal. The influx of freshwater accelerates the breakup of the sea-ice - an area of ice the size of Australia will soon vanish from the Arctic. On land, a woolly bear caterpillar emerges from the snow having spent the winter frozen solid. Caterpillars normally become moths within months of hatching, but life is so harsh here that the woolly bear takes 14 years to reach adulthood. Once mature it has only days to find a mate before it dies! Alongside the caterpillars white Arctic wolves race to raise their adorable cubs before the cold returns.
Chris investigates how nature's masterminds measure up against human brain power. Looking at a variety of animals, such as ravens, crows, bees and starlings, Chris explores how different animals can use tools, solve complex puzzles, recognise themselves in mirrors and even reason like humans.
Attenborough describes the course the Amazon, starting high up in the Andes of Peru, whose streams flow into the great river. Young rivers are by nature vigorous and dangerous: they flow fast and form rapids, thick with mud and sediment.
Tanzania's Mount Kilimanjaro is the highest freestanding mountain and volcano in the world. Join wildlife expert Jean du Plessis as he makes the perilous summit climb through its five vastly different climates to understand how quickly its famed glaciers are melting.
The world's biggest beasts have always captured the imagination. But whilst being big can have its advantages, it also comes with sizeable challenges. Take the world's largest lizard, the Komodo dragon, whose huge appetite means it must take on prey ten times its weight, or the tallest animal of them all - the giraffe - who, with such a long neck, must control immense blood pressure. Nature's biggest beasts must go to extraordinary lengths to thrive. These are their epic survival stories!