The Central American land bridge, which was formed in the Pleistocene Epoch 3 million years ago has provided a pathway for the interchange of many species of wildlife between North and South America, contributing greatly to the biodiversity of both hemispheres. The accelerating degradation of Central America's rich endowment of flora and fauna can be largely attributed to widespread habitat degradation and destruction. Forest fragmentation threatens many species and entire ecosystems. What remain are islands of wild land in a sea of civilization.