Trevor Hughes

USA TODAY

WASHINGTON, D.C. -- Citing concerns about users harassing other visitors and wildlife, the National Park Service on Friday banned remote-controlled airplanes and helicopters at all of America's 401 national parks and memorials.

Park service director Jonathan B. Jarvis signed an order directing park superintendents to ban visitors from using the small personal aircraft, often called drones or unmanned aerial vehicles.

Several parks already prohibit such devices; Jarvis' order expands the ban to cover all 84 million acres managed by the park service.

The remote-controlled aircraft usually carry cameras aloft, allowing pilots to snap photos or record videos from vantage points normally inaccessible from the ground. Some of the craft, which are about the size of a pizza box, buzz loudly as their multiple propellers keep them airborne.

In a statement, the park service cited three recent examples of pilots disturbing park users and animals:

-- Last September, an unmanned aircraft flew above evening visitors seated in the Mount Rushmore National Memorial Amphitheater. Park rangers confiscated it.

-- In April, visitors at Grand Canyon National Park watching the sunset were interrupted by a unmanned aircraft flying and eventually crashing in the canyon.

-- Later that month, volunteers at Zion National Park saw an unmanned aircraft disturb a herd of bighorn sheep, reportedly separating adults from young animals.

Jarvis' order calls for further study of the issue, but permits park managers to keep using drones and UAVs for research and search-and-rescue purposes. Some formally approved uses by hobbyists may still be permitted, the park service said in a statement.