Motorized, remote-controlled aircraft -- or drones - are now banned in all parks under the jurisdiction of the East Bay Regional Park District, including Shadow Cliffs in Pleasanton.
"As more and more people get drones, they're becoming an increasing safety hazard for aviation," said Lt. Lance Brede of the East Bay Regional Park District Police force. "It really can be a life and death situation, and we're very concerned about the public's safety as well as our own."
In addition, drones can pose a safety threat and be annoying and intrusive for other park visitors, Brede added.
He said drones are extremely dangerous for helicopters and airplanes, adding that even a small drone could shatter a windshield or collide with an aircraft's propellers or fuselage, causing the aircraft to crash and potentially kill all on board.
Drones are also disruptive for wildlife, especially birds, according to Cindy Margulis, executive director of the Golden Gate Audubon Society. The park district is home to several re-bounding populations of special-status birds, including bald eagles and peregrine falcons, and protecting them is a high priority.
"Recreational drones can scare birds away from essential activities like feeding, roosting, and nesting," she said. "While a single drone flushing birds into flight may not seem disruptive, when this happens over and over, birds are unable to get the food and rest they need to survive."
Citations for violating the drone ordinance cost about $300.
Motorized model airplanes are also illegal in the parks, but non-motorized remote-controlled gliders are allowed in specified areas in three parks: Coyote Hills Regional Park and Mission Peak Regional Preserve in Fremont, and Del Valle Regional Park in Livermore.
Since Dec. 15, the Federal Aviation Administration requires owners of drones to register with the agency before flying outdoors. Even so, drones are illegal in East Bay Regional parks regardless of whether the owner has registered.
The National Park Service, as well as dozens of state and local park districts across the country, have banned drones. These include all California state parks, including Mt. Diablo State Park, except with a film permit.