Slaughter of the Innocents: Yes, Uncle Sam Is Really Planning to Kill 16,000 Prairie Dogs

Eagles and owls will also likely die in the pointless poisoning, biologists say.

(Photo: Massimo De Nino/Getty Images)

Jan 10, 2014· 3 MIN READ
Richard Conniff is the author of House of Lost Worlds: Dinosaurs, Dynasties, and the Story of Life on Earth and other books.

Sometimes just trying to get along with a difficult neighbor can make us prisoners in our own homes. It can lead us to do things that go against our stated intentions and interests. That seems to be the situation right now for the Thunder Basin National Grassland, a 547,000-acre protected area in northeastern Wyoming.

The U.S. Forest Service, which manages the Grassland, has announced a plan to poison an estimated 16,000 prairie dogs and dramatically shrink the already limited area in which prairie dogs are tolerated. Thunder Basin officials intend to do it despite their declared plans to improve prairie dog habitat. Their method, moreover, is likely to kill a lot of other wildlife in the affected area and, incidentally, squander taxpayer dollars for nothing.

USFS is proposing the outlandish venture under pressure from neighboring cattle ranchers and politicians, particularly Wyoming Gov. Matt Mead, and to appease “a dedicated few who cling to archaic, erroneous concepts” about prairie dog biology. The quote comes from Jason A. Lillegraven, a vertebrate paleontologist who has retired from the University of Wyoming but still finds himself dealing with dinosaurs.

Just five years ago, the same Thunder Basin managers set aside 85,000 acres as one of the last refuges in the American West where prairie dogs could not be poisoned, gassed, shot for target practice, set on fire, or otherwise harassed into extinction. The thinking then was straightforward: Only 2 percent of America’s prairie grasslands remain intact, and Thunder Basin represents one of the best remnants of that storied heritage. Meanwhile, black-tailed prairie dogs have lost an estimated 99 percent of their habitat.

Giving them a tiny scrap of land on which to survive seemed to make sense in part because so many other species that are emblematic of the American West depend on them: Their burrows provide homes for mountain plovers and burrowing owls, and the prairie dogs themselves are a favorite prey of golden eagles, ferruginous hawks, and swift foxes, among others. Thunder Basin has targets to increase populations of all those predators. It also ranks high up among the candidate sites for transplanting a population of endangered black-footed ferrets—and the ferrets cannot live if there aren’t enough prairie dogs for them to eat.

Nearby ranchers, on the other hand, regard prairie dogs as a menace on multiple counts and want them gone. So the new plan calls for killing any prairie dog within a quarter mile of private land.

Other prairie dog poisoning campaigns—and they are legion—have generally relied on zinc phosphide, which is fast-acting, with minimal risk of secondary poisoning to other species. But prairie dogs that survive a whiff of zinc phosphide may learn to steer clear of it.

The new plan calls instead for using the notorious anticoagulant Rozol. “Rozol makes creatures that ingest it bleed from every orifice and stagger around for the week or two or three it takes them to die, attracting predators and scavengers,” the environmental writer Ted Williams reports. “Whatever eats the anticoagulant-laced victim dies, too.”

Using Rozol requires lots of taxpayer-funded labor to monitor the area and pick up carcasses before scavengers can get to them. But in most cases the monitoring gets forgotten, says Williams. The unintended victims include “golden eagles, bald eagles, ferruginous hawks, owls, magpies, turkey vultures, badgers, swift foxes, coyotes, raccoons, red-winged blackbirds, wild turkeys, and almost certainly, ferrets.”

What’s the argument for killing prairie dogs? Ranchers sometimes cite the threat of plague—and the black death certainly sounds terrifying enough. But it typically affects fewer than 10 people each year in the United States, and if caught early, is easily treated with antibiotics. Victims tend to be wildlife biologists and hunters. In the rare cases where the victim hasn’t directly handled a sick animal, it’s generally because a free-roaming house cat has wandered into an infected prairie dog town. The way to prevent the problem isn’t by killing prairie dogs but by dusting prairie dog towns to minimize fleas.

The larger problem is that any prairie dog town is messy, a warren of burrow holes and bare earth. That can make a rancher feel like a sloppy land manager. Ranchers tend to refer to prairie dogs as invaders, though fossil evidence is clear that prairie dogs predate cattle ranchers by quite a bit (about 2 million years, or longer than humans have been a species).

The visual evidence also suggests to ranchers that the prairie dogs are eating grass that ranchers feel rightly belongs to their cattle, but the scientific evidence on competition with livestock is mixed. Pronghorn, elk, and bison actually prefer to graze in prairie dog towns, evidently because the prairie dog wastes make for vegetation that’s richer in nitrogen. And a 2013 study found that prairie dogs can make things better for livestock too, at least when it rains. Unfortunately, they make it worse in a drought, and it’s human nature that the credit you get for making a good thing better is not nearly proportionate to the blame you get for making a bad thing worse. The West has been enduring drought conditions for more than a decade, and that makes the prairie dog a handy scapegoat for desperate ranchers.

Is that reason enough for USFS managers to reverse every carefully laid plan for the protection of wildlife in an area that has, after all, been set aside largely for wildlife and recreation?

“I have a strong sense that they do not want to do this,” says Steve Forrest of Defenders of Wildlife. “They don’t have the budget for it, and they know in their hearts that it makes no sense.” Their own fact sheet says any gain in weight for livestock from getting rid of prairie dogs is worth less than the cost of proposed poisoning. “But when the governor of Wyoming speaks, they have to pay attention.”

The managers at Thunder Grass National Grassland declined to be interviewed for this article. They’re probably too embarrassed. But you can email district manager Tom Whitford at

Better yet, contact Wyoming Gov. Matt Mead here, or at 307-777-7434, and also let your own representatives in Congress know what you think.