Habitat loss is identified as a main threat to 85 per cent of all species described in IUCN Red Lists - an account of the threatened status of thousands of plant and animal species. For centuries, landscapes have been altered by humans through deforestation, fire and over-use. The result is often a simplification of habitats that has led to the local loss and ultimate extinction of species and an overall loss of biodiversity. Urbanisation too has dramatically increased the rate of habitat loss and change. The construction of roads, expansion of towns and the construction of dams and canals destroy or alter vast areas of natural habitats worldwide.
Deforestation is one of the leading causes of habitat and biodiversity loss.
As tropical forests contain at least half of the Earth's species, the clearance of some 17 million hectares each year is causing a dramatic loss of biodiversity. As the world population exceeds six billion people, the pressure on land for building and agriculture, in particular, add to concerns for biodiversity conservation. When habitats are fragmented into small areas, they support fewer species. Many birds and mammals need large areas in which to feed and breed. The negative effects of habitat fragmentation on biodiversity can sometimes be improved by maintaining strips of habitat between two fragments.