Flock of trouble

Biologist William Boarman peered through a night-vision scope at power transmission lines that appeared thick and laden with unidentified objects. Squinting into the twilight, he spied about 2,200 ravens perched shoulder to shoulder across a quarter-mile of wires near Twentynine Palms, roosting after a day of scavenging across the desert.

If the scene seems ominously reminiscent of an Alfred Hitchcock film, that’s because the big black birds portend a profound ecological change in the Mojave Desert and beyond. As more humans inhabit the West, ravens multiply exponentially as do their detractors, and the birds are blamed for a host of problems.

“When I grew up back in the ‘70s, ravens were pretty uncommon,” says Boarman, a researcher for the U.S. Geological Survey’s Western Ecological Research Center in San Diego who has studied ravens for 14 years. “Crows were in flocks and ravens were alone or in pairs or in threes, but now ravens are everywhere.”

The birds interfere with radar-absorbing material used for research at the Naval Weapons Center at China Lake. Military pilots landing planes near the Marine base at Twentynine Palms say flocks are growing so large they may affect flights. Pecan farmers in the Mojave and almond farmers in the Central Valley say ravens eat their crops.

And the birds exact a heavy toll on the desert tortoise, the state reptile and a threatened species. Ravens peck through the soft shells of young tortoises and eat them. A U.S. Geological Survey and University of Redlands study of more than 600 raven nests in the Mojave last year showed tortoises were part of the menu at 6% of the nests.

Amy Fesnock, a wildlife ecologist at Joshua Tree National Park, says cursory inspection beneath some raven nests shows “literally hundreds of baby tortoise shells found under them.”

The number of Mojave ravens has grown by more than 1,500% in 30 years, government surveys show. Other studies show burgeoning populations in Southern California and the Central Valley.

Following the trash trail, ravens near Edwards Air Force Base in the developing west Mojave thrive on a diet consisting mainly of rubbish, and smaller populations of birds inhabit cleaner, more remote desert areas, a recent Geological Survey study shows.

“They are very adaptable and social birds,” says Glenn Olson, executive director of the Audubon Society’s California office. “They’re omnivorous and can take advantage of waste products in a garbage can outside McDonald’s or pick off a young tortoise or eat chicks in a nest or eat at a landfill. They are out of balance with nature and we need an active management program.”

One of the smartest birds in nature, ravens belong to a big-brained family of birds that includes magpies and jays. Ravens trail troops into battle, follow wolves to prey and may even guide predators to the next meal. Bigger than crows, they make a deep croaking sound rather than a caw-caw, and they use crude tools to get food.

Ravens soar over much of the nation, but they thrive in the California desert, sustained by open spaces and abundant trash from rapidly growing towns.

To control the birds, the U.S. Fish and Wildlife Service is considering a nevermore option: poisoning or shooting ravens in the Mojave and portions of Nevada.

Bernd Heinrich, professor emeritus of zoology at the University of Vermont and author of “Mind of the Raven,” says people hate ravens because they have long been associated with death.