Castle Rock Area In Mount Diablo State Park to Close for Falcon Nesting Season


Walnut Creek, CA.

The California Department of Parks and Recreation (Ca. State Parks) announced on January 22, that the area known as “Castle Rock” in Mount Diablo State Park will be closed to visitors from February 1st to July 31st to help protect the American peregrine falcon (Falco peregrinus anatum). This protected species is territorial and highly sensitive to disturbance during nesting season. The rocks – located in Pine Canyon – are closed to all access during these same months each year.

This site was a historic nesting location for the bird, known by naturalists and scientists dating back to the late 1800s. The falcons disappeared from the area by the early 1950s due to the use of the pesticide DDT. In the 1990s, Save Mount Diablo and the East Bay Regional Park District cooperated to release captive-bred peregrines at the site; they have since resettled at the site.

“This magnificent falcon was endangered, but it has returned to its historical nests sites on the rocks of Pine Canyon, thanks to the banning of DDT and reintroduction by the Santa Cruz Predatory Bird Research Group in cooperation with California State Parks, the East Bay Regional Park District, and funders,” said EBRPD Wildlife Manager Doug Bell, who has studied the birds.

California State Parks has partnered with East Bay Regional Park District, the operator of Diablo Foothills Regional Park, which neighbors the closed area, to educate rock climbers and the general public of this closure and the importance of protecting the falcon. Signs and educational panels will be placed in the area to advise and educate users about the closure. Rock climbers will be encouraged to utilize an alternate climbing area of the park during the closure. 

“We encourage the falcons to nest here by trying to protect the site during the breeding season,” noted Diablo Foothills Park Supervisor Bridget Calvey. “Closing the area gives the falcons peace and quiet so they can produce the next generation.”

The distinctive Castle Rock formations are actually located within Mount Diablo State Park. However park visitors often access them from the Stage Road Trail, which follows Pine Creek through Castle Rock Regional Recreation AreaDiablo Foothills Regional Park, and the state parkThe off-limits area includes all of the Castle Rocks east of the Stage Road Trail and Pine Creek. The Stage Road Trail itself is not affected and will remain open. Pine Creek is the boundary between Mount Diablo State Park and the two adjacent regional parklands.

“There are plenty of other trails to explore in the area,” noted Calvey. “We hope visitors will take the opportunity to get to know other routes – and share them with their friends.”

Although the peregrine is no longer endangered, it is still a fully protected species in California, and disturbance of nesting peregrines is punishable by fines and even arrest.

Please abide by the posted regulations, and don’t disturb the nesting birds. Public cooperation will be key to the success of the program.

California State Parks Mission
To provide for the health, inspiration and education of the people of California by helping to preserve the state’s extraordinary biological diversity, protecting its most valued natural and cultural resources, and creating opportunities for high quality outdoor recreation.

The East Bay Regional Park District is a system of beautiful public parks and trails in Alameda and Contra Costa counties east of San Francisco Bay, established in 1934. The system comprises 119,000 acres in 65 parks including over 1,250 miles of trails for hiking, biking, horseback riding and nature learning.

 Photos of peregrine falcons courtesy of EBRPD wildlife volunteer Mary Malec.

Peregrine Falcon
Peregrine Falcon


Peregrine Falcon

Map preview of area (above). Download as PDF

Ryen Goering