Kirsty Young's castaway is the naturalist, Chris Packham.

TV presenter, filmmaker, writer, photographer, every bit of his work revolves around wildlife. If he's not busy telling us why we should love midges he's enthusing about the hearing capacity of a barn owl. His passion for animals is clear, what they think of him remains a little more uncertain; he's been attacked by a baboon, charged by lions and bitten by a puff adder.

His obsession with the natural world began early when a predictable boyhood fascination for tadpoles and ladybirds grew to encompass mosquito larvae, lizards, snakes and bats. As a teenager he collected badger droppings by day and pogoed with electric blue hair at Clash gigs by night.

These days he distinguishes himself by his impressive knowledge of his subject and his outspoken views on everything from countryside culls to the problems with cat owners.

He says, "I'll never rest until I've tried to do my own small bit in terms of changing the environment so it's a better place. I won't do it for my grandchildren because I won't have any and I won't do it for yours. I'll do it because it's the right thing to do."

Producer: Cathy Drysdale.