Ecology Ablaze

Animals and plant seeds can then move between the areas, reducing the threat of inbreeding or local disasters wiping out a species. And they provide more space for top carnivores such as jaguars who range long distances to survive. That's why the network of connected areas as a whole has more ecological value than the sum of its parts.

"Because you don't have intense migrations like in the African savannah, your corridor can serve its purposes and still allow certain kinds of human uses," explains Archie Carr III, a veteran conservationist who leads the Wildlife Conservation Society's projects in the Caribbean. Carr led a project between 1990-95 called the Paseo Pantera (Spanish for "path of the panther") that originally established the corridor system that later became the CBM.

Coffee, for example, had traditionally been grown under the shade of trees. This kind of coffee field mimics the structure of a natural forest and thus provides good habitat for wildlife.

"Some of this shade-grown coffee would provide corridor functions probably perfectly well for an enormous number of tropical creatures," Carr says.

Photo courtesy CBM. People and wildlife often live in close proximity in Central America, and their needs sometimes conflict.

But in modern times, a more productive, sun-tolerant strain of coffee was introduced to the region, leading to treeless coffee fields with little habitat for wildlife. Various organizations including the CBM and the Rainforest Alliance are now trying to persuade coffee farmers to return to the more ecological, shade-grown system.

It's not easy for the region's environmental managers to keep an eye on such a large area of land, though. That's why the intergovernmental agency in charge of the corridor, called the Central American Commission for Environment and Development (CCAD), has recruited the bird's-eye view of NASA satellites to help out.

"The landscape-wide perspective that satellites provide is essential for doing a large-scale conservation project like this," Irwin says.

"The rain forest is so thick in many places that you can hardly see 10 feet in front of your face," Irwin says. "Trying to survey such large areas on foot is nearly impossible."

To get the job done, Irwin and his colleagues use data from an assortment of satellites. For assessments on the scale of entire countries, they use data from the Moderate-resolution Imaging Spectrometer (MODIS) on NASA's Terra and Aqua satellites. This sensor takes images whose pixels each cover 250 meters of ground, suitable for looking at such large scales. Landsat, on the other hand, has a resolution of 30 meters, and is more useful for closer looks.