Mt. Diablo closes park area where peregrine falcons nest

For the first time ever, a corner of Mt. Diablo State Park will be closed to the public for six months so that peregrine falcons can nest in peace in the region. Pine Canyon, which includes the area known as “Castle Rock,” closed on Feb. 1 and will remain off-limits until July 31 so that the territorial and highly sensitive raptors, a “highly protected species,” will not be disturbed during their important nesting season.

The main access to Castle Rock is through Foothill Regional Park, which prompted East Bay Regional Parks

The peregrine falcons are not just important to our modern-day ecology. In antiquity, the falcon represented the rising sun in Egypt. Egyptian gods, including RA, were often depicted with the head or body of the falcon. The bird is known to symbolize visionary power, wisdom and guardianship.

The peregrine falcons have been nesting in the Castle Rock area since the late 1800s, but by the 1950s they were nowhere to be found and were listed as an endangered species. According to investigations by scientists, the pesticide known as DDT nearly wiped out the falcon population by affecting the calcium in their eggs.

In 1990, however, Save Mount Diablo, the park district and the University of California were able to reintroduce the species by slipping some captive peregrine falcon eggs into a prairie falcon nest on Mt. Diablo. Their numbers have rebounded and they are now listed as a “highly protected species.”

Michael Marchiano, a volunteer with the Mt. Diablo Interpretive Association and an enthusiastic naturalist and bird watching tour guide, is ecstatic over the closure.

“It’s not just the falcons that will benefit,” says Marchiano. “Many other birds use the area to nest, including golden eagles, red tail hawks and red shoulder hawks in the high trees, cooper’s hawks, kestrels, barn owls, prairie falcons, swifts, cliff swallows, barn swallows and many other songbirds nest in cavity spaces in the rocks.”

In the last five years, vandalism, spray paint, beer cans, broken glass and garbage has increased exponentially in the Castle Rock area, Marchiano says. “Rock climbers often crawl into the cavities where the nests are, scaring off the parents who may never return. Places like Sentinel Rock and Rock City provide much better rock climbing opportunities on the mountain.”

According to a National Geographic article, falcons can migrate up to 15,000 miles in a year — the name peregrine means wanderer — and some nesting sites have been used for hundreds of years by successive generations of falcons. They are known as the fastest bird, reaching up to 200 miles an hour while diving for prey.

Often, part of the elaborate mating ritual is for the male to show the nesting site to the female, who may base her decision on its desirability. Falcons mate for life and can live up to 17 years in the wild.

Signs and educational materials will be placed in the area to advise and inform users about the closure, said district officials. Violators will be subject to fines.