Most plants and animals are those common to southern India, but there are additional varieties. The plant life ranges from that of the equatorial rain forest to that of the dry zone and the more temperate climate of the highlands. Tree ferns, bamboo, palm, satinwood, ebony, and jak trees abound. The wide range of mammals, birds, and reptiles once found in Sri Lanka has been reduced by the conversion of forests into rice fields, but water buffalo, deer, bear, elephants, monkeys, and leopards are among the larger animals still present. The Ceylon elk ( sambhur ) and the polonga snake are unique to Sri Lanka. Birds are numerous, many varieties from colder countries wintering on the island. Sri Lanka has well-organized game and bird sanctuaries. Insects abound and numerous fish are found in the shallow offshore waters.