In this fourth episode, Iolo Williams explores how birds in Wales have adapted to living alongside us, making use of our buildings, parks and gardens and even the waste we throw away. One of the most notorious urban birds is the gull and Iolo explains why these very adaptable and intelligent birds are doing so well in Cardiff
Mammals' ability to learn new tricks is the key to survival in the knife-edge world of hunters and hunted. In a TV first, a killer whale off the Falklands does something unique: it sneaks into a pool where elephant seal pups learn to swim and snatches them, saving itself the trouble of hunting in the open sea. Slow-motion cameras reveal the star-nosed mole's newly-discovered technique for smelling prey underwater: it exhales then inhales a bubble of air ten times per second. Young ibex soon learn the only way to escape a fox - run up an almost vertical cliff face - and young stoats fight mock battles, learning the skills that make them one of the world's most efficient predators.
Svalbard in the Arctic spends many months of the year in complete darkness, an unrelenting frozen winter with temperatures down to -40 Celsius. But when the sun finally reappears, the landscape magically transforms from an ice world into a rich tundra, full of exotic plants, birds, arctic foxes, polar bears, walrus and reindeer. This film captures the changes in all their glory and reveals how this transformation is only possible thanks to some bizarre micro-organisms that feed on ice and the stunning abilities of migrating birds.