The Peregrine Falcon is the swiftest of all birds of prey, slightly larger than a crow, with and nondescript coloration of brown, grey, and white. Peregrine falcons are one of the most widely distributed species of birds, nesting on every continent except Antarctica. The world’s largest urban population of nesting Peregrine Falcons can be found in New York City.
A peregrine falcon can spot its prey from six miles away. Tucking in its wings, diving like a missile, changing direction with precision, ruffling its feathers to control speed, and slamming its talons into its quarry mid-air. Its beak has a type of tooth that acts like a wire cutter, severing the spine of its prey in an instant. Peregrines are avian predators and feed almost exclusively on other birds. Most of their prey is caught on the wing. Peregrine falcons diving at prey has been clocked at speeds of more than 200 mph, making them among the fastest animal on earth.
Peregrine falcons have never been very abundant. Studies in the 1930s and 1940s estimated that there were at least 200 breeding pairs of peregrine falcons in the eastern United States. Then, beginning in the late 1940s, peregrine falcons suffered a devastating and rapid decline. By the mid-1960s, the species had been eliminated from nearly all the eastern U.S.
In the mid-20th century, peregrine falcon populations took a nosedive due to the DDT pesticide poisoning. DDT moved through the food chain from insects, fish, and birds and moved up to larger carnivores, like the peregrine falcon. DDT caused harsh chemicals to build up in the falcons’ fat tissues, reducing the amount of calcium in their eggshells. With thinner shells, the eggs would be easily crushed when incubated by the parent falcons.
DDT was finally banned in 1972, and a partnership between scientists and falconers worked together to breed the birds in captivity and release them to places where they had traditionally nested, including New York City. Peregrines naturally prefer cliffs as a habitat, so the city’s canyons and skyscrapers provide desirable nesting spots for them, along with an abundance of food like pigeons, starlings, and sparrows.
Due to restrictions on the use of DDT, and intensive captive breeding and reintroduction programs across the United States and Canada, the peregrine falcon has made a remarkable comeback. Peregrines have been returned to much of their natural range and have reclaimed many historic breeding sites.
Thacher State Park is home to a 6-mile section of the Helderberg Escarpment, an exposed limestone cliff reaching several hundred feet high. An ideal nesting location for peregrines. Peregrines don’t build nests; they dig an indentation in the ground or in rock cliffs, called a “scrape”. The Helderbergs were a historic nesting ground in the 1950s and earlier. Since the ban on DDT, peregrines were not spotted around the Helderbergs until 2016 when a mated pair was discovered flying around the southern section of the park.
Since 2016, the Helderberg falcons have been monitored for nesting attempts. In 2021, the mated pair was found nesting with a clutch of eggs, but the nest was abandoned after a few weeks for unknown reasons. In 2022, the falcons have been spotted very early in the year, around February. With increased sightings and activity in the southern section of the park. Park staff and visitors are hopeful that this year will be a successful nesting season and may bring 3 to 5 new peregrine chicks into the world.