Peregrines were nearly wiped out in the era of DDT. Dichlorodiphenyltrichloroethane was widely used as an agricultural and urban pesticide during the 50s and 60s.
The potent poison, which led to Rachel Carsons classic environmental book "Silent Spring," built up in the falcons bodies as they ate prey that, in turn, had eaten insects and plants contaminated with the chemical. The result was diminished fertility, plus eggs with shells so thin, they broke under the parents weight.
By 1970, there were only 39 known pairs of peregrines in the lower 48 states.
Peregrines are one of the success stories of the environmental movement. DDT was banned in the early 70s and the birds, once near extinction, were removed from the Endangered Species List on Aug. 20, 1999.
Their incursions into the human sphere have made them very popular. Bird watchers line up in metropolitan areas like Toronto and New York City to view peregrines that are nesting in skyscrapers. In the Midwest, power plants have been popular nesting sites for the raptors. Peregrines are found all over the world, including South Dakota. However, the birds have not returned in numbers to traditional nesting sites like the bluffs and cliffs along the Missouri, and repopulation of that type of habitat remains a goal of peregrine supporters.
Peregrines are dark blue/bluegray across the top of the head, back, wings and tail with light bars across the tail and a dark stripe down the face. The underbelly is light-colored with a pattern of irregular dark streaks along the wingspan and vertically across the breast and legs. Like all raptors, peregrines have a sharp hooked beak for tearing food.
Peregrines range from about 15 to 20 inches and female peregrines are larger and stronger than the males. Female peregrines (falcons) are about the same size as a crow, generally weighing in at around 2 pounds. The males (tiercels) weigh about a third less. Peregrines can live for up to 15 years.
Diving peregrines have been clocked at more than 200 miles an hour.
Peregrines usually begin breeding at about 2 years of age. Females lay a clutch of 3 to 5 eggs. Newly hatched peregrines double their weight in just six days and and increase tenfold by three weeks. Hatchlings are covered with white down, replaced by feathers in 21 to 35 days. Peregrines first fly 35 to 45 days after hatching. They begin to hunt around 60 to 80 days.
Peregrines are found all over the world except in Antarctica and the Pacific Islands. The most common subspecies in the United States, falco peregrinus anatum, is found from central Alaska to central Mexico and usually winters in South America.
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