Peregrine Falcons In Mendoland
by Kate Marianchild, November 11, 2009
Peregrine falcons, the fastest birds on earth, like Mendocino County. In fact, our county has more peregrines breeding here than any other county in the lower 48 eight states. They nest on cliff ledges 50-200 feet above the ground and seem to favor our county's isolated rocky cliffs and knolls, our mild climate, and the abundant birds available for hunting. Not many birds of prey are fast and agile enough to rely on birds as their primary food source, but with diving speeds of up to 273 miles per hour and the ability to make quick turns, these falcons are the ideal predators of other flying birds.
Once it was extremely rare to see a peregrine falcon racing in hot pursuit of ducks or doves in Mendocino County. From 1950-1975 populations fell dramatically in the US to the point that by 1965 the birds were almost extinct east of the rockies and were at 10% of their former numbers in the west. Abandoned nest sites were common on the cliffs and ledges of Mendocino, and by 1975 only 15 pairs of peregrine falcons were known to be nesting in the entire state of California.
Enter Dr. Monte Kirven, one-time Ukiah-based biologist and upcoming speaker for Peregrine Audubon Society. In 1966, Dr. Kirven and other biologists began to study breeding peregrine falcons, collecting the data that eventually revealed the role of DDT and other toxic chemicals in the now well-known problem of eggshell thinning. Their research was instrumental in the passage of the 1992 federal legislation that banned DDT.
In 1981, nine years after DDT was banned, Dr. Kirven was assigned to Ukiah's Bureau of Land Management office to see how peregrine falcons were faring in our region. He scoured Mendocino National Forest, as well as Six Rivers, Shasta, and Trinity National Forests, by helicopter and by foot, finding many previously unrecorded active nests as well as nests that had once been abandoned and were now reoccupied. He describes his Ukiah-based years as the most important of his 25-year study of peregrine falcons. Eleven years after arriving here, Dr. Kirven and a Santa Cruz-based scientist, Dr. Brian Walton, were able to publish a paper that reported an increase in California's breeding peregrine falcon population from 15 pairs in 1975 to 113 pairs in 1992! Dr. Kirven describes it as “a conservation success of unprecedented magnitude that resulted in the recovery of the most spectacular member of our wildlife heritage, the American peregrine falcon.”
Look for a medium-sized raptor with pointed wing tips, a uniform pattern of fine dark and light lines over most of its underside, and a large dark “mustache” on each cheek. You might see it flapping rapidly or diving and twisting through a flock of birds, causing them to scatter. If you would like to thank someone for the almost forever-lost opportunity to see such a sight in our county, you will soon have an opportunity to do so.
Dr. Monte Kirven, now a Santa Rosa resident, will present a slideshow on California's peregrine falcons on Thursday, November 19, 7pm at the Ukiah Civic Center. The slideshow will include great photographs of falcon nests and chicks.
This Peregrine Audubon Society presentation is free to the public, though donations will be welcome. The Ukiah Civic Center is at 300 Seminary Avenue. To join Peregrine Audubon Society and receive a newsletter with regular announcements about programs and field trips, please send $15 to PAS, PO Box 311, Ukiah, CA 95482.