Armed with the latest global scientific research, Chris Packham and Liz Bonnin battle it out to find the definitive answer to the burning question - which are best, cats or dogs? Part 1: The animals go head to head in a series of rounds testing different aspects, beginning in this edition with intelligence, sensory powers and physical prowess. On the search for answers, dog-lover Chris comes face to face with a pack of wolves, while feline fan Liz confronts an Arabian wild cat to discover how the relationship humans and their pets have evolved.
The Cave of Swallows in Mexico is a 400m vertical shaft, deep enough to engulf the Empire State Building. The Lechuguilla cave system in the USA is 193km long and 500m deep with astonishing crystal formations hanging from its chambers. Although often overlooked, caves are remarkable habitats with equally bizarre wildlife. Cave angel fish cling to the walls behind cave waterfalls with microscopic hooks on their flattened fins. Cave swiftlets navigate by echo-location and build nests out of saliva. The Texas cave salamander has neither eyes nor pigment. Unique access to a hidden world of stalactites, stalagmites, snotites and troglodytes brings a wealth of surprises.
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.