Despite its proximity to the continental mainland, Madagascar’s animal life developed in isolation after the island broke away from the rest of Africa about 135 million years ago. It is estimated that 90 percent of the species inhabiting its tropical forests are endemic, meaning that they are found nowhere else in the world. Madagascar has some 25 species of lemurs and 30 species of tenrecs, a type of insectivore. Other native mammal species include several civets and the fossa, a member of the cat family measuring almost 1.5 m (5 ft) in length. Madagascar’s bird and insect populations are equally rich and are also largely endemic.
Because more than 90 percent of Madagascar’s forests have been affected by human activity, many species on the island face extinction because of loss of habitat. Many other notable species have already vanished, including the giant lemur, giant tortoise, and elephant bird.