Further, breeding programs helped baby birds survive and Peregrine Falcons were reintroduced into areas where they had disappeared. Although DDT is still used in some areas outside of the U.S., its use worldwide has been much reduced. Joint efforts by many countries and groups helped the species recover. More needed to be done to protect Peregrine Falcons, however, because they migrate through other countries and needed protection there, too. They measured the amount and types of toxins in the Peregrine Falcons’ feathers and eggs. In Alaska, scientists tracked the number of breeding Peregrine Falcons nesting along the upper Yukon River. Efforts started soon after to help the species recover, led by the U.S. law that protects imperiled species and their habitats.
In 1973, Peregrine Falcons were listed as endangered under the Endangered Species Act (ESA). Peregrine Falcons disappeared completely from the eastern U.S. By the 1960’s, many species of birds, including Peregrine Falcons, declined across North America because of DDT. As a result, nesting birds produced fewer chicks. The fragile shells made the eggs susceptible to being crushed in the nest. In Peregrine Falcons and other birds, one effect of DDT was to interfere with egg formation, resulting in eggs with thin shells. As Peregrine Falcons fed on contaminated birds, the contamination was passed on to them in ever-increasing amounts. When birds ate insects contaminated with DDT, they themselves became contaminated. But DDT had other, unintended effects on the environment. It was used to kill insects that were pests on crops and that caused human diseases. Damage From an Insecticide and Help From a Lawĭichloro-diphenyl-trichloroethane, or DDT for short, is an insecticide introduced in the U.S. As a top predator in the ecosystem, human activities such as pollution and climate change can threaten Peregrine Falcons. Though they are powerful predators, the species has faced difficult challenges. Using their sharp vision, they target prey in mid-air, chase it, and strike with a sharp blow of their talons. This helps them catch their favorite meal-other birds. Diving from above, they can reach over 322 km/h (200 mi/hr). Peregrine Falcons are among the fastest birds in the world. (B) Biologists travel by motorboat and use binoculars and spotting scopes from riverbanks to look for Peregrine Falcons on bluffs (photo credit: Josh Spice, NPS).įalcons are birds of prey, meaning they hunt other animals for food. Inset shows the location of the preserve in Alaska with national park lands in green. Yukon-Charley Rivers National Preserve, Alaska, is outlined in green and the straight green line at the right of the map shows the boundary with Canada.Figure 2 - (A) The upper Yukon River flows 266 km (165 miles) between the Canadian border and Circle, Alaska.Each summer, Peregrine Falcons return to the upper Yukon River from their winter ranges, as far away as Argentina, to mate and raise chicks. They provide a safe place to raise young and good viewing to look for prey. The high, steep, golden bluffs found here are an important Peregrine Falcon nesting habitat. A preserve is like a national park created to protect wildlife, habitat, and history. We monitor these birds along a 265-km (165-mi) section of the Yukon River in Yukon-Charley Rivers National Preserve ( Figure 2A), in Alaska, U.S. They have bright yellow, clawed feet called talons, used for perching and catching prey ( Figure 1B). Peregrine Falcons are large, stocky falcons with dark, slate-colored feathers on their backs, lighter feathers on their stomachs, and distinctive facial markings ( Figure 1A). The upper Yukon River in Alaska is home to one of the world’s most well-studied populations of American Peregrine Falcons. is a shining success story of the Endangered Species Act, although climate change and other pollutants create continuing challenges for the species.
The Peregrine Falcon’s recovery in the U.S.
Today, upper Yukon River Peregrine Falcons have rebounded and are thriving. Fish and Wildlife Service, National Park Service, and others helped Peregrine Falcons recover. Eventually, Peregrine Falcons were listed as endangered under the Endangered Species Act in the United States (U.S.). Thin eggshells meant that eggs crushed easily in the nest, which reduced the number of baby birds produced. Peregrine populations decreased in the 1960’s because widespread use of the insecticide DDT caused their eggshells to thin. American Peregrine Falcons nesting along Alaska’s upper Yukon River have been studied for nearly 50 years.
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