The Peregrine Falcon

Since the 1970's, federal and state wildlife agencies have been releasing peregrine falcons in urban areas to help restore the species after it had been decimated by pesticide poisoning. Peregrines naturally nest on cliffs and mountain ledges, so they were preadapted for city living. One of their favorite foods is pigeon. A peregrine will hurtle from its perch on a high-rise ledge or bridge tower at speeds sometimes exceeding 320 kilometers (200 miles) per hour. It kills its prey on the wing, and returns to the nest to feed. In terms of pigeon control, peregrine reintroduction had only modest success because the falcons fiercely defend territories of up to 8 kilometers (5 miles) around their nests. Thus, even the largest cities have space for only a few pairs of falcons—hardly enough to make a serious dent in the local pigeon population. Nevertheless, the program has boosted the peregrine population, and they now swoop around major cities all over North America.

Many bird species native to America have embraced cityscapes as readily as introduced species. One example is the nighthawk. An insect eater, the nighthawk has learned that the city's heat creates rising columns of air that send hordes of insects spiraling upward. Emitting a nasally "peent" that sounds like an electronic pager, it dives and swerves to catch insects on the wing on dark summer nights. The species also has adapted its nesting behavior to city life. Whereas in the wild, nighthawks nest on the ground in open fields, city birds nest on flat rooftops, which provide security from predators.