Peregrine Falcons

March 09, 2015 Posted by: JG - Entrance Station Ranger (Arch Rock)
As a child, I visited Yosemite many times, and I always enjoyed watching the wildlife. I’d seen deer, coyotes, bears, countless squirrels, and everything seemed plentiful. However, on one of my visits, a park ranger at Glacier Point took some time to talk to me about one of the park’s less abundant species: the endangered peregrine falcon (Falco peregrinus).

The peregrine falcon is the fastest animal on earth. Soaring hundreds of feet in the sky, the peregrine falcon uses its keen eyesight to spot smaller birds, such as waterfowl, doves, and song birds. With its prey in sight, the peregrine falcon will fold its wings back, and dive towards its target. Reaching speeds of over 200 miles per hour—faster than a NASCAR racer—the peregrine falcon snatches its prey out of mid-air.

Unfortunately, like many birds of prey, including the bald eagle, the peregrine falcon was severely impacted by the use of the pesticide DDT. In a process called biomagnification, DDT levels in peregrine falcons increased as they preyed on birds that ate insects or other insectivores. As a result of this increased concentration, peregrine falcon eggs became dangerously thin. So thin, in fact, that the parents would crush their own eggs while trying to incubate them. Peregrine falcon populations plummeted, the birds were listed as an endangered species, and the use of DDT was banned.

Fortunately, peregrine falcon populations have recovered, and the falcon was delisted in 1999. However, it remains on California’s endangered species list, and has special status in Yosemite. In order to protect our peregrine falcons, certain climbing areas in Yosemite are closed during the falcons’ nesting season.

These areas include the granite cliffs towering above the Arch Rock Entrance Station. Today, nearly twenty years after listening to a ranger talk about peregrine falcons at Glacier Point, I myself am a ranger at Arch Rock. Every spring, I look up at the cliffs, and wait for the peregrine falcons to make their appearance. I watch them soar through the air, and listen to them call to each other. Eventually, those calls are mixed with those of the newborn chicks, and before I know it, the fledglings are learning to fly. Seeing the next generation of peregrine falcon always reminds me of the species’ recovery, and it gives me hope.


El Portal, Nature Scene

Last updated: April 9, 2015

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