Habitats range from coastal mangroves, swamps, heath, grasslands and blue gum forests. Most koalas on the mainland of Australia suffer from the chlamydia disease. French Island provides the world's most dense and disease free group of koalas. They are often moved to repopulate diseased areas on the mainland. Shelter is provided for more than 100 species of bush orchids, and 260 species of birds. Significant species on the island include: King Quail, the critically endangered Orange-bellied Parrot, Fairy Tern, White-bellied Sea Eagle, Swamp Skink, Long-nosed Potoroo.