Sir David Attenborough tells the stories of the world's best animal architects. There are house-proud bower birds, who only find a mate if they decorate their homes perfectly. There are hornets, who build electric central heating systems, and the star-nosed mole, whose house is designed so well that worms, his favourite meal, literally drop in for dinner. From larders to nurseries and from high-rises to subway systems, Attenborough shows that the animal architects have designed it long before humans.
The incredible reef life and the birds, lizards and reptiles who cope with the lava rock islands of the Galapagos make this remote series of islands a unique natural habitat. The Panama and Humboldt currents regulate the seasons and the rhythm of life onshore and off.
There is no greater test for life than winter, as temperatures plummet to 70 below and winds reach 200kph. Darkness and ice extend across the polar regions and only a few remarkable survivors gamble on remaining. We join a female polar bear trekking into the Arctic mountains to give birth as the first blizzards arrive. Out on the frozen ocean, the entire world's population of spectacled eider ducks brave the winter in a giant ice hole kept open by ferocious currents. Arctic forests transform into a wonderland of frost and snow - the scene of a desperate and bloody battle between wolf and bison, but also where a remarkable alliance between raven and wolverine is made. Beneath the snow lies a magical world of winter survivors. Here tiny voles dodge the clutches of the great grey owl, but cannot escape the ultimate under-show predator - the least weasel. Midwinter and a male polar bear wanders alone across the dark, empty icescape. Below the snow, polar bear cubs begin life in an icy den while fantastical auroras light the night skies above. In Antarctica, we join male emperor penguins in their darkest hour, battling to protect precious eggs from fierce polar storms. Weddell seals escape to a hidden world of jewel-coloured corals and alien-looking creatures but frozen devastation follows as sinister ice stalactites reach down with deadly effect.