Cut off from the rest of the world , islands have evolved their own unique and rich wildlife. This biodiversity adds much to the beauty of small islands, and their people rely heavily on it for their economic, social and cultural well-being. Yet its very isolation and rarity makes it particularly vulnerable, both to human activities, such as felling forests and draining wetlands, and to other species brought in from outside. One-sixth of all the world's threatened plant species live only on islands. And the islands of Oceania now have more endangered bird species than any other region on Earth.
Tourism is an important and growing source of income and employment for many small island states.
It accounts for over a quarter of the total economy of the Caribbean and provides a fifth of all its jobs, and is increasing rapidly in the Indian Ocean and the Pacific. Yet it also often spoils the very environment on which it depends, as mangroves and wetlands are destroyed for development, coral reefs are damaged by yachts and divers, and hotels discharge raw sewage into the sea. Small islands have little space to put their wastes. Sewage is mainly pumped out to sea, without treatment, and pollution is increasing with the growth of population and tourism. Coral reefs are among the richest and most beautiful ecosystems on Earth.