Monty Don presents Shared Planet, the series that looks at the crunch point between human population and the natural world. In this programme Howard Stableford reports from Conneticut on the complex decline of the once very ubiquitous Chimney Swift, a story Monty Don believes is the paradigm for the series. The wider issues of human population and nature are explored in the studio with Lord May, past president of The Royal Society and from Vienna, Professor Wolfgang Lutz, a specialist in human population dynamics.