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This story was first published on June 12, 2015, as part of our Bird Files series.

Fifty years ago the world’s fastest bird was endangered, nearly wiped out from the pesticide DDT. Today, the peregrine falcon has made its comeback in, of all places, cities.

Urban peregrine falcons are so successful in Pennsylvania cities that there are now more peregrines in towns than there are in the countryside. 

Nature blogger Kate St. John explains why.

LISTEN to the story

Peregrine Falcons are nature’s fighter jets, famous for their spectacular 200-mph dives. They’re built for speed with pointed wings, special cones in their nostrils to deflect the wind, and a see-through third eyelid that protects their eyes like racing goggles. They need this equipment for hunting birds which they capture in midair.

Peregrines’ agility and speed allow them to outmaneuver other birds. And they’re so fierce and reckless, they will defend their nests against hawks—and even eagles —and win.

About the size of crows, peregrines are charismatic birds—charcoal gray and white with dark heads and a dark vertical bar on each cheek called a malar stripe. When alarmed, they emit loud “kakking” sounds to scare off intruders and express their displeasure.

Peregrines traditionally nested high on cliffs in a simple bowl they scraped in dirt or gravel. Though never plentiful, by 1970, there were no peregrine nests east of the Mississippi. DDT, a pesticide that accumulates in the food chain, caused peregrines and other birds of prey to produce thin eggshells that broke during incubation.

After the U.S. banned DDT in 1972, falconers and wildlife agencies worked together to reintroduce peregrines to eastern North America. Captive breeding programs released the nestlings to the wild in special boxes placed on cliffs, but those nestlings were eaten by predators because they had no parents to defend them.

Soon people came up with another idea. Tall city buildings resemble cliffs and don’t have predators, so the boxes were moved to city rooftops where the young birds had great success. Once peregrines found the city they decided to stay. They now nest on buildings and bridges near a handy source of food—pigeons.

You can see city peregrines easily on Internet nestcams that provide close-up views. But check them out soon. After the youngsters fly, the nest is empty until the next spring.

Read Kate St. John’s week-by-week guide to Peregrine development.

Nestcams in Pennsylvania

Why I’m Addicted to Bird Nestcams (and You Should be Too)

Bird calls for the audio recording of this segment come from The Macaulay Library at the Cornell Lab of Ornithology, recorded by Gerrit Vyn.