The author studied the ecology and breeding behaviour of Indian Grey Hornbill Ocyceros birostris for two years in Nagpur city in Central India. The hornbills have a hornlike protrusion or casque over their bills. The hornbills have an interesting breeding behaviour. The female seals herself in a living tree cavity till the nestlings are grown enough to accept the food through a small cavity slit. She fledges and the cavity is resealed by the nestlings. They break it when they are ready to fly. This is the only hornbill species in India which breeds in well wooded metropolitan cities. The keystone species in the diet of hornbills were figs of Ficus religiosa and F. benghalensis making up nearly three fourth of its diet during breeding season. The hornbills indulge in various social interactions like bill grappling, aerial jousting and erratic chases in the canopy. The role of bark pieces supplied to nest inmates in nest sanitation was established by the author.