From down in the undergrowth to high above the treetops, we see how mammals have conquered every level of the forest with perfect camouflage, secret messages, and even the power of flight, but now many face new challenges as they are forced to adapt to a changing world.

With fur designed to keep you warm, keeping cool is never going to be easy, yet mammals are found in the hottest, driest places on earth such as Australia's barren outback, where they have found remarkable ways to stays cool, find water, and beat the heat.

Thanks to their great ingenuity, combined with a thick fur coat, mammals can survive where no others can, in the cold of the planet's extreme frozen worlds. Here we see a polar bear learn remarkable new hunting skills and witness the rarely seen caring side of the not so mythical wolverine.

Very few mammals have managed to lose all ties with land and conquer life in water, one of the greatest challenges for an air breathing mammal. Those that have are some of the cleverest of all, forming surprising bonds not just amongst their own but with other species as well.

It is two decades since Sir David looked at the "Life of Mammals." In that time the issues facing mammals have grown and grown – today, less than 6% of the world's mammal biomass is made up of wild mammals, and many face extinction. As well as bringing a fresh understanding of this remarkable group of animals we highlight many of the problems faced by mammals in a rapidly changing world. To do this, we explore how mammals are coping living alongside perhaps the most successful mammal of all – us, revealing both winners and losers in today's new wild.

Originally confined to the night during the time of the dinosaurs, many mammals have, with heightened senses verging on superpowers, become masters of the shadows. Today, some are even returning to the dark side as their daytime world gets more and more crowded.