All naturalists have personal obsessions with particular species or activities which may, to non-naturalists, seem ridiculous . In this five-part series Matthew Oates, naturalist and ecologist with the National Trust, meets the people for whom nothing in the natural world is out of bounds. Today he explores the world of twitching rare birds with Rob Lambert, from the University of Nottingham. Rob has travelled around the UK amassing a huge list of over 450 species of birds and he's keen to show Matthew a rare long-billed dowitcher at Slimbridge in Gloucestershire. But Matthew wants to know if this is just trainspotting or are there other benefits to be gained from twitching. According to Rob Lambert, it's all about tribes, memories and experience. and birds too.

Presenter: Matthew Oates
Producer: Brett Westwood
Editor: Julian Hector. Show less