For centuries Jamaicans have exploited their island for mahogany and other cabinet woods, leaving little of the natural rainforest still standing. Erosion of the hill slopes is one serious consequence of this exploitation. But there is still a rich flora of native orchids and ferns. Throughout the year the many species of tropical and subtropical plants produce a changing spectacle of colours. Among the plants are the vivid red poinciana, the yellow poui, and the blue lignum vitae, which is Jamaica’s national tree. There are four major botanical gardens. Jamaica has more than 200 species of birds, including a beautiful hummingbird–known locally as the “doctor bird”–which is the national bird. Also abundant are bats, mongooses, frogs, lizards, and crocodiles. There are no venomous snakes on the island but many species of ants.