Raju joined the Bombay Natural History Society (BNHS) as a field biologist at Point Calimere and worked with S. A. Hussain and was a pioneering Indian bird ringer. In 1971, he set up a bird banding camp at Lambasingi village in the Eastern ghats of Andhra Pradesh where, he along with Selvin Justus discovered the presence of the little spiderhunter a species then known to be isolated in the Western Ghats and found again only in northeastern India and Southeast Asia.