Wyofile by Mike Koshmrl

PINEDALE — Red, green, white and purple lights danced from the ear of one of Albert Sommers’ white-snouted calves as the cattleman lurched his side-by-side buggy forward.

It was 9:18 p.m. and dark was closing in on historic Sommers Ranch, which stretches out along the east bank of the Green River. There aren’t usually major issues with carnivores picking off naive calves on this privately held pasture. But there will be plenty of that in the months to come, especially after the ranch herds the same calves onto Bridger-Teton National Forest grazing allotments, where there’s chronic conflict between grizzly bears and livestock

“A bear’s going to be hitting about now,” Sommers said. “This is the time: dusk.” 

That’s where the dancing lights come in. There is hope they will slow the bovine bloodshed this summer. 

The idea behind the solar-powered LED devices, which now adorn several thousand calves and sheep in eight states, is that their unpredictable flashing colors will cause predators to pause. Utah State University professor Julie Young, whose research focuses on reducing human-wildlife conflict, came up with the idea after watching drone-captured footage of lighted sheep herded into patterns and even made to play ping pong

“There was a video of herders — I think they were in Wales — and they were having their sheep run around and form Christmas trees,” Young said. “It was stupid, I probably saw it on like Twitter.” 

Still, the video got the former Animal and Plant Health Inspection Service-Wildlife Services employee thinking. Young knew that using flashing lights fixed in one spot has proven to provide some protection against canines like coyotes and wolves. Its effectiveness, however, wanes as the canids grow accustomed to where the lighting is located. But what if the light source was always moving?    

Wildlife conflict-reduction researchers retrofitted valve stem LED lights purchased from Amazon.com so that they could be worn by cattle and sheep. “They’re little solar lights designed to go on car rims, so when kids drive through the city they look really sweet,” Utah State University PhD student Aaron Bott said. (Mike Koshmrl/WyoFile)

“Canids pursue their prey,” Young said. “So as all the sheep or all the cows start moving around, all these lights will suddenly start flashing. The idea is that the canid, being fearful of the flashing lights, it might disrupt the behavior long enough so that the livestock can escape.” 

Proof of concept

First, Young and her collaborators had to come up with a design. She enlisted the help of wildlife biologist Stewart Breck, who works for the U.S. Department of Agriculture’s National Wildlife Research Center. An engineer friend of his took on the task of determining how to integrate the light onto identification ear tags commonly used in agriculture. As for the lights, they came from Amazon.com. 

“They’re little car light devices that you screw onto your valve stem,” Breck said. “And when you start driving they flash different colored lights, and different kinds of patterns.” 

The light part of the device alone retailed for just shy of $4 a piece. Though that may sound cheap, it’s “pretty expensive,” Breck said, for a cattle rancher or woolgrower looking to deploy dozens or hundreds at a time. 

“I think we can build them for a lot cheaper,” he said. “They’re pretty clunky right now and the way they attach to the tags, it’s not ideal. There’s a lot of problems to fix.” 

Rep. Albert Sommers irrigating on his ranch near Pinedale. The cattleman is one of three Sublette County ranchers testing out a new technology to curb livestock depredation. (Angus M. Thuermer, Jr./WyoFile)

Nevertheless, even substandard prototype flashtags were effective when they were first tried out in summer 2021. One goal of that trial, attempted with a sheep herd near Stanley, Idaho, was to see if the motion-triggered flashing bothered the livestock. 

“We actually would go out at sunset and sunrise and collect behavioral data on the sheep, to see if they were behaving differently than the ones that weren’t wearing the tags,” Young said. “We weren’t seeing any differences.”

At the same time, the LED lights did seem to afford some protection against predators. About 75 of the 300-member Idaho sheep herd got the flashtags, and although just 25% were lit, the whole population held up. 

“Every year that same herd suffers depredation by wolves,” Young said, “and last summer there were no depredations by wolves.” 

Some early results from a much more extensive trial in 2022 are equally promising. That one involved a Utah woolgrower who was experiencing “severe” coyote depredation on his small herd, Young said. All seven sheep that remained in that band got the flashtags. 

“One of the sheep stuck its head through a fence and ended up ripping out the ear tag,” Young said. “And that was the only sheep that got killed by a coyote since we put the ear tags in.” 

For his dissertation, Utah State University PhD student Aaron Bott, whom Young is advising, is investigating how wolves use human-dominated landscapes in order to mitigate conflicts. One chapter looks at the flashtags, 4,000 of which are being deployed in Arizona, New Mexico, Nebraska, Wisconsin, Montana, Idaho, Oregon and Wyoming after Amazon.com’s car rim lights were cleaned out. 

Scaling up

“That was our limiting factor for putting them out on the landscape, because everybody wants to try something to minimize depredation,” Bott said in mid-May. “By word of mouth, we’re still getting requests — even yesterday — for people requesting to be a part of this study.” 

Utah State University PhD student Aaron Bott inadvertently puts on a light show with a LED depredation-reduction eartag device inside a utility closet at Montana State University in Bozeman, Montana on May 17, 2022. (Mike Koshmrl/WyoFile)

Some 600 of those tags were deployed to Wyoming’s Green River basin, he said. Sommers and another cattle rancher who’s also a part of the Upper Green River Cattlemen’s Association obtained 500 of them, and 100 or so went to a Sublette County woolgrower.

“We’re trying to get as much variety as possible,” Bott said. “These were designed to work primarily with canids, but some people who are experiencing depredation in wolf country are primarily experiencing bear depredation. We don’t give out any promises that it’ll work with bears, but it can’t hurt to try.” 

There are some early indications that grizzlies’ savvy might be too great for the night-lit livestock. Grizzlies already nabbed a “couple” flashtag-wearing Montana calves, Young said, though she noted that the bovines were “really young.” 

“We don’t know if the lights were actually flashing when the bear attacked,” she said. “At least in one case, they confirmed that the calf was asleep.” 

Even if the flashtags aren’t effective against grizzly bears, the devices still have promise as a new minimal-maintenance, non-lethal tool that could help curb coyote and wolf depredation. Current area-based deterrents, like fladry and electric fencing, can be time-consuming and expensive to set up, or provide only fleeting effectiveness. 

About 600 calf cattle and sheep in the Green River basin will be wearing prototypes of an LED eartag device that’s being tested to see if it slows depredations from coyotes, wolves and grizzly bears. (Mike Koshmrl/WyoFile)

Calves are being fitted with ear tags anyway and there’s promise, Beck said, that a commercial manufacturer could be intrigued by the product and bring the price down. One goal of this years’ more widespread deployment is to determine if the tool can be cost-effective. 

“It’s going to increase your costs some,” Young said. “But maybe it’s less than the cost of losing an animal.” 

For now, all the lighted tags are being provided to cattle and sheep ranchers for free. Wildlife Services, which has a $1.4 million budget to develop non-lethal predator damage management tools, is funding the project. 

‘Worth a shot’

Sommers, who’s also Sublette County’s representative in the Wyoming House, approached the research team about participating. 

“It’s easy to do,” he said, “and it’s worth a shot.”

“Hell, it might even turn out that it attracts [grizzlies]. Maybe every one of these damn things gets killed. Then we’ll know it’s not a good idea.”


Out in his buggy checking out the LED-flashing calves as the daylight waned that night, Sommers admitted he’s not sure what to expect. 

“Hell, it might even turn out that it attracts [grizzlies],” Sommers said. “Maybe every one of these damn things gets killed. Then we’ll know it’s not a good idea.” 

If the flashtags do work to deter calf-craving grizzlies, there’ll be no better place for them than the Upper Green. The U.S. Fish and Wildlife Service once authorized the killing of up to 72 federally threatened grizzlies over a 10-year period as a result of the 267-square-mile grazing allotment, where wildlife managers confirmed more than 500 conflicts with cattle between 2010 and 2018.

Issues with grizzlies, Sommers said, have not abated.

“Confirmed losses, I think we were in the 70s last year,” he said. “And calves missing, I’m sure we’re still close to 200.”

WyoFile is an independent nonprofit news organization focused on Wyoming people, places and policy.