A Biological Superpower

A Biological Superpower

Costa Rica's forests hold an array of flora and fauna so vast and diverse that scientists haven't even named thousands of the species found here. The country covers less than 0.03% of the Earth's surface, yet it contains nearly 5% of the planet's plant and animal species. Costa Rica has at least 9,000 plant species, including more than 1,200 types of orchids, some 2,000 kinds of butterflies, and 876 bird species.

Costa Rica's biological diversity is the result of its tropical location, its varied topography, and the many microclimates resulting from the combination of mountains, valleys, and lowlands. It can also be attributed to Costa Rica's geological youth. Five million years ago this patch of land didn't even exist -- in its place was a huge canal separating North and South America, where the Pacific and Atlantic oceans flowed together. About three million years ago the movement of tectonic plates created the land bridge that is now Costa Rica and Panama, which became a pathway for flora and fauna that had never coexisted.

Costa Rica's enormous natural diversity is in many ways the result of the intercontinental exchange, but the country's flora and fauna actually add up to more than what has passed between the continents. Although it is a biological corridor, the isthmus also acts as a filter, a hospitable haven to many species that couldn't complete the journey from one hemisphere to the other. The rain forests of Costa Rica's Caribbean and southwestern lowlands, for example, are the most northerly home of such southern species as the crab-eating raccoon and the dreaded jungle pit viper known as the bushmaster. The tropical dry forests of the northern Pacific slope are the southern limit for such North American species as the white-throated magpie-jay and the Virginia opossum. And then there are the tourists -- migrants, that is -- such as the dozens of northern bird species that spend their winter holidays in Costa Rica, among them the Tennessee warbler, western tanager, and yellow-bellied sapsucker. Costa Rica's many physical barriers and microclimates have also fostered the development of indigenous plants and animals, such as the mangrove hummingbird and mountain salamander.