I was hot, sweaty and itchy from bug bites, but I was exactly where I wanted to be: in the untrammeled remote reaches at of Aberdeen Proving Ground in Maryland, entrusted with the lives of five endangered peregrine falcon fledglings. A 20-year-old college student in 1978, I felt lucky that The Peregrine Fund had chosen me to spend the summer as a hack site attendant—a falconry term for someone who feeds, waters and protects the birds before they fly off into the wild. That summer provided me an opportunity to participate in a remarkable recovery effort. Back then, peregrine falcons sat on the edge of extinction, compromised by DDT. The pesticide—banned in 1972—accumulates in tissues and interferes with eggshell formation. Falcons were laying eggs with such thin shells they often broke during incubation or otherwise failed to hatch. To help them recover, biologists began breeding the falcon in captivity and releasing them in the wild in 1974.