The Indian rhinoceros is the largest of the Asian rhinos. It has a single horn, which can be as long as 53 cm and, like all rhino horns, is composed of keratin rather than bone. The skin is grey-brown and has many loose folds and tubercles, giving an armour-plated appearance. Indian rhinoceroses are often accompanied by ‘tick birds' (several species, including mynas) and egrets that ride on their backs, and are thought to feed on parasites between the folds of skin. Egrets also forage on the insects exposed by the moving feet of the rhino. Males have large, sharp incisors that may be used in fights over females in the breeding season.