As the sun rose over a plateau near Bryce Canyon National Park, prairie dog biologist Barbara Sugarman and her three-person crew clocked in before the critters awoke. They’re here to test a new way to protect these Utah rodents from the Black Death.
Yes, the same bubonic plague that killed at least a third of the population in Medieval Europe — tens of millions of people.
All Sugarman and her team need these days, though, is a little luck and a lot of peanut butter.
“I like to think of trapping as an art form,” the Utah Division of Wildlife Resources scientist said. “It sounds really easy to outsmart a 2-pound rodent. It's not.”
The team is trying to capture prairie dogs in peanut butter-baited live traps to give them a check-up. It’s been one year since the animals got their first dose of Fipronil — a common flea prevention medicine for dogs and cats.
In the Middle Ages, the bacterial disease that causes the plague spread through flea-bitten rodents. The same thing has happened in prairie dog towns nationwide over the last few decades. So, scientists want to see if the medicine can prevent it by killing the insect carriers.
“Pets get protected against fleas and ticks by ingesting these active ingredients,” Sugarman said. “What if we did that with prairie dogs?”
To get the rodents to eat it, the medicine is wrapped in little peanut butter balls dubbed FipBits. Scientists at the U.S. Fish and Wildlife Service and U.S. Geological Survey developed this method. Because it’s technically classified as a drug, Sugarman needed to get a prescription from the state veterinarian to try it in Utah.
“The ‘patient’ are the prairie dogs,” she said with a laugh. “I've never helped write a prescription before.”
And it’s easy to tell if the little patients are taking the medicine. It turns their poop blue, she said.
A prairie dog plague outbreak poses little threat to humans. You’d have to get up close and personal to catch it, and it’s easily treatable with an antibiotic. But prairie dogs don’t go to the doctor when they feel sick.
They live in close quarters underground — the opposite of social distancing. So, an outbreak in a colony is often cataclysmic.
“It can kill 95% to 100% of individuals within a few days,” Sugarman said. “It's very devastating.”
That matters because prairie dogs are considered a keystone species because of their place in the food chain.
“They're on the menu for everything,” she said. “Raptors, snakes, badgers, coyotes, foxes. You name it, they eat prairie dogs.”
They are also the prairie’s little architects, building networks of underground tunnels up to 30 feet long that often include a nursery and bathroom. Those burrows become homes for burrowing owls, snakes and smaller rodents after the prairie dogs move out.
This particular species of prairie dog only lives here in south-central and southwest Utah. If it disappears, scientists don’t know what ripple effects it could create across the landscape.
“We've only just hit the tip of the iceberg in terms of what we understand about a lot of the ecosystem and world around us,” Sugarman said.
‘We could lose everything that we've worked for’
Before Europeans arrived, the population of prairie dogs in North America was in the billions. Settlers viewed them as vermin and poisoned them and shot them in droves. Their numbers plummeted.
Plenty of people still don’t like prairie dogs today, Sugarman acknowledged. Some farmers and ranchers argue that they destroy agricultural land. Utah communities, including Cedar City and Parowan, have also complained about the little diggers undermining their airports and other development.
After decades of extermination, habitat loss and disease outbreaks, Utah prairie dog numbers reached dire lows in the mid-20th century. They got listed as threatened under the Endangered Species Act in 1973, and a key part of the federal recovery plan is plague prevention.
If the FipBits are proven to work, Sugarman said it could be a vast improvement over the alternatives. Current flea prevention tactics typically involve spreading a powder insecticide called deltamethrin dust at each burrow opening. It’s time-consuming and expensive, she said, costing agencies thousands a year.
Initial research indicates that FipBits might cost 90% less than the dusting method, Sugarman said. That means agencies could save money or treat larger pieces of habitat for the same amount. There are around 1,300 prairie dog colonies in Utah, Sugarman said, and some cover hundreds of acres. Rather than dusting every burrow opening, the FipBits are tossed out in a 10-meter grid, making it easier to scale.
It may also help plague prevention efforts survive a future budget cut.
“Let's say there's a year where we don't get funding for dusting,” Sugarman said. “We could lose everything that we've worked for for decades. It's serious.”
Promising research published by other scientists, including David Eads for the U.S. Geological Survey, indicates the FipBit method lowers the number of fleas in other prairie dog species and can reduce plague risk.
In Sugarman’s Utah study, her team inspected prairie dogs living within two 25-acre plots. One is the test site where the FipBits were distributed, and the other is the control. When she checked her test subjects one month into the study in the summer of 2024, the medicated ones had significantly fewer fleas.
“FipBits definitely had a big impact,” she said. “The next question is: How long is it effective for?”
That’s why her one-year check-up is crucial.
Saving a success story
After placing dozens of traps at dawn, the crew returned to the test plot every 45 minutes to see if any doggies took the bait.
Olivia Elkin climbed up onto a truck bed for a higher vantage point. She’s a wildlife technician based at Bryce Canyon through the American Conservation Experience organization and collaborates with Sugarman’s team on this project.
“If you have a good view of the trap, you can tell pretty quickly if the door is open on the front,” she said as she scanned the horizon through binoculars.
They want to do the trap inspection quickly so their presence doesn’t spook the animals. And after hours of work, it would be nice to spot one.
“They're just so cute to watch, honestly,” Elkin said. “If there's enough sun, they kind of look like little golden orbs.”
By the end of the day, the crew still hadn’t captured a single prairie dog. Still, crew lead Jonathan Leberman said all data is valuable, even if the number is zero.
“Sometimes you get skunked. You get nothing,” he said after checking some empty traps. “But that's still good. It's all part of it.”
It’s possible the lack of prairie dogs here meant the FipBit medicine doesn’t protect them from fleas for a full year, Sugarman said, and the plague had already swept through.
Other clues point that way.
Scientists know the plague has been present near here — Sugarman’s team confirmed a case in Bryce Canyon last year. There wasn’t any noticeable evidence of a predator. At another nearby test plot, the crew placed nearly 100 traps the previous day and only captured three dogs. Some were in rough shape.
“We had one animal with 45 fleas,” the most Sugarman said she’d ever seen on a Utah prairie dog. “I see that animal and I'm like, ‘Hmm, time to put more FipBits out.’”
This research could help scientists learn how to best adjust the number of FipBits they distribute in the future if this approach is approved and scaled up for wider use.
Right now, Sugarman said Utah’s plan is for another round of test FipBits this year with an additional check-up in 2026. At some point, the urgency of the situation will compel them to take action to protect the animals in habitats that aren’t getting the test medicine. She said some of those control groups have seen significant population declines, likely because of the plague.
Despite the bleak situation, there are still signs of hope. Prairie dogs reproduce quickly. So populations can bounce back if given the chance.
This year’s spring survey found Utah prairie dog numbers have grown nearly six-fold since the grim lows of the 20th century — from an estimated statewide population of 15,766 in 1976 to around 90,000 in 2025.
“It was estimated that the species would be extinct by the year 2000. It's still here,” Sugarman said. “So, this is one of the happier success stories.
If that trend continues, she said the resilient rodents could eventually come off the threatened species list — as long as the Black Death doesn’t undo their progress.
This story was edited with assistance from Sáša Woodruff of Boise State Public Radio.
