From the editor.

• Author: Kiernan, James Patrick

In the next fifty years, more than 10 percent of the earth's existing biological species will be extinct, according to a recent scientific report. The specific causes are many, but a disturbing number are a result of human behavior. It seems that not since some catastrophic age many centuries ago are we, or at least our children, to be faced with such changes in our natural environment.

In this issue of Americas, we look at two species under examination by scientists and environmentalists, and while the prognoses are different, in neither case is success certain. Jeffrey Cohn travels to the land of the saguaro, the most studied and recognizable columnar cactus in the Sonoran Desert of Arizona and Sinaloa, Mexico, which has suffered a steady decline over the past century. And from Guyana, Chris Hardman describes efforts to protect the giant river otter. Demand for its velvety fur has eliminated the affable "river dog" from most of its range in South America told made it one of the most endangered animals on earth.

We also mark two exceptional feats of survival and success. Jane Regan writes about the...