Also important is a high proportion of endemic species, especially in the case of geographically isolated areas. Such regions havo unique evolutionary histories and fixed boundaries to species ranges, and thus, degradation of such habitats is more likely to take a toll on animals. Striking examples are the Philippines and Madagascar, where 32 and 44 percent, respectively, of all mammal species are threatened. In both countries, well over half the species are endemic, and habitat disturbance is high. Less than a quarter of the species in the U.S. and only 4 percent in Canada are endemic.
Habitat disturbance is moderately above average in the U.S. and very low in Canada.
The countries with the most threatened mammals are Indonesia, with 128 species, and China and India, both with 75. These three account for 43 percent of the world's population and are among the most densely populated. There are many reasons for protecting birds, not the least of which is the delight we take in watching them. Birds, like other animal groups, are most threatened in island habitats, and indeed, of the 104 bird species that became extinct in the past 400 years, about 90 percent lived on islands. Island species, particularly in the tropics, are often found nowhere else on the planet and therefore cannot be replenished from outside.