We chose this photo of a peregrine falcon—a female, walking across the rail of a balcony in Chicago—to inspire hope on Endangered Species Day. Not every animal listed as endangered is doomed to extinction. Peregrine populations were decimated by the use of pesticides, such as DDT, in the mid-20th century. The chemicals accumulated in the birds’ bodies, causing weak eggshells and high mortality rates for chicks. But by the 1980s humans had learned the cause, reduced or eliminated the various chemicals, and helped the birds rebound with gusto.