Doctor John Dolittle is the central character of a series of children’s books by Hugh Lofting. He is a doctor who shuns human patients in favour of animals, with whom he can speak in their own languages. He later becomes a naturalist, using his abilities to speak with animals to better understand nature and the history of the world. (summary from Wikipedia)
On Librivox: http://librivox.org/the-voyages-of-doctor-dolittle-by-hugh-lofting/
On Amazon: http://www.amazon.com/Voyages-Doctor-Dolittle-Hugh-Lofting/dp/1605124680/ref=sr_1_1?ie=UTF8&s=books&qid=1261696389&sr=1-1
