Ravens could spell doom for desert tortoises

A raven perches on a Joshua tree in Queen Valley in Joshua Tree National Park.

Smart, family-oriented and ravenous, ravens are taking over the skies and telephone wires across the desert. The question is whether more fragile desert dwellers — especially the desert tortoise — can survive their new neighbors.

Common ravens were once migratory birds, but in the Western desert, they’ve quit migrating and made themselves at home permanently.

“They realized it was kind of nice in the desert now,” Allison Fedrick told around 20 people gathered for a lecture in the Hi-Desert Nature Museum Thursday. “We have golf courses, we have shade, we have all kinds of nice things for our ravens.”

As the human population exploded in the desert, the ravens flew close behind. Across the Mojave Desert, their populations increased more than 700 percent in the last 40 years. Around Ridgecrest, the raven population has increased by 1,500 percent, according to Fedrick.

“Where there used to be 10 ravens, there are now 15,000 ravens,” she said.

And where there are 15,000 ravens, there is a huge problem for the animal species they prey on, like young desert tortoises.

Elsewhere in the desert, they also eat fringe-toed lizards and sage grouse eggs. All three species are threatened by the ravenous ravens.

“For the desert tortoises, there’s no greater threat than the abundance of ravens,” Ron Berger, president of the nonprofit Desert Tortoise Preserve Committee, told Audubon magazine this year.

Research scientists say the ravens are multiplying thanks to human additions to the land, like water from farms and sewage facilities and food from garbage and road kill.

“They can pretty much eat and digest everything,” Fedrick said.

With human population comes the water, garbage and road kill that sustain the ravens, but some people also just feed ravens as though they were pets.

“People feed them because ravens build up those relationships,” Fedrick said. Ravens are known to give gifts to those who feed them and “talk” to them with their croaking caws.

Even without purposeful feedings, ravens can live on the things humans leave behind. “They can survive on trash,” Fedrick told the room.

As they thrive in their newly permanent desert homes, ravens are preying on desert tortoises — and not just hatchlings. In the past, they were known to only eat young tortoises, whose shells were still soft. Now, they’ve learned to peck in between the shell and gular horn that projects under the tortoises’ necks to get to the soft body in between.

Nonprofits and animal groups like the Living Desert have been trying to educate people about the trash and water they leave out so that ravens will stop proliferating around human habitation.

But others say there’s a simpler solution: Open fire on hungry birds. Elsewhere in the desert, some farmers have gotten licenses to hunt ravens, which are normally protected by the Migratory Bird Treaty Act.

“A lot of people are done with education. They think it’s time to cut down on the population ourselves,” Fedrick said.

“That is a difficult decision and it is almost never a good idea.”

Slashing one animal population can have unintended effects. For example, she said, at one time in Yellowstone, mule deer were aggressively hunted because they were overpopulating the park. One effect was the number of wolves, which eat the deer, also dropped.

A policy of killing ravens indiscriminately also just wouldn’t be effective in the long term, according to Audubon’s Brian Rutledge. “If we are going to handle this population crisis, then we must think about the long term,” he told the magazine.

Limiting the birds’ access to human sources of food and water is a better solution, he believes: “Then the raven population will slowly shrink to a healthy level.” 

The Living Desert is part of a coalition of groups hoping to use education and outreach to protect desert tortoises.

The Living Desert runs a campaign called Time to Talk Trash. Outreach specialists like Fedrick give presentations encouraging people to cover their trash and secure their trash can lids, since ravens are strong and smart enough to get past lightweight, unsecured lids.

The Coalition for a Better Environment worked in Ridgecrest, California City and Mojave in 2016 to teach business owners about the raven problem and how they could help by covering trash. Compliance jumped across most communities and raven dumpster visits decreased, according to the CBE. 

“If we can duplicate these kinds of results in other towns, we may have a good chance to help local endangered wildlife,” Executive Director Lawrence Alioto told Audubon.

The CBE recommends working with local governments and trash companies like Burrtec to enforce trash container regulations.

“All cities and counties have existing trash, water, and other public health and safety ordinances that — if enforced — could have a significant impact on reducing raven population growth,” the CBE concluded.

Tim Shields, a tortoise biologist and owner of Hardshell Labs, is looking at technology to save the tortoises and the ravens. He’s developed a laser that startles and repels ravens without harming them.

Fedrick is hopeful that some of these methods will make a dent in the raven population and preserve the desert tortoise — which is, after all, California’s official state reptile.

“Our state mammal is the California grizzly bear and it’s extinct,” she said. “It would be heartbreaking to lose another state animal.”

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