LEARNING TO LIVE WITH PRAIRIE DOGS - A pair of Montana ranchers is showing that cowherds can exist in harmony with these native animals

National Wildlife, April-May, 2001 by Christie Aschwanden

So Uresk decided to do the experiments himself. "We asked, 'If you get rid of prairie dogs, how much forage do you gain?' The answer was about four to seven percent," says Uresk. "It does impact the rancher in dollars and cents." But the costs of poisoning prairie dogs (borne largely by the federal government) outweigh the gains made by eliminating the animals. Because the government pays, however, "Ranchers think, 'Why not poison them if it's free?'" he adds.

Tranel Sr. sees plenty of reasons not to poison them, although he and his son give predators a boost by building poles for raptors and digging trenches where foxes can hide. "It's like a zoo around the prairie dog towns. We've got foxes, snakes, hawks, badgers, plovers and burrowing owls." With prairie dogs around, these species flourish. Uresk's research shows that prairie dog towns have roughly twice the number of species as similar areas without the dogs.

The black-tailed prairie dog is what biologists call a keystone species. Lose the keystone, and the whole ecosystem crumbles down with it. Researchers once believed that as many as 208 species depend on prairie dogs, but a recent review of published data by Natasha Kotliar and her colleagues at the U.S. Geological Survey in Colorado revealed that those estimates were probably too high. Kotliar found strong evidence for nine species relying on prairie dogs, including the endangered black-footed ferret, which feeds almost exclusively on the animals; the mountain plover, a bird that requires the disturbed grassland habitat prairie dogs provide; the burrowing owl, which uses prairie dog burrows for homes; and the ferruginous hawk, which preys on prairie dogs. Evidence for other species was not as strong, or data wasn't available, but Kotliar's study nonetheless confirmed the prairie dog's role as a keystone species.

Prairie dogs do more than just serve as prey, they also perform a valuable service for the prairie-they disturb it. In addition to digging up the soil, prairie dogs clip the vegetation around their burrows, enhancing nitrogen uptake by these plants. "Natural disturbances are an important part of maintaining the prairie ecosystem," says Kotliar. "We're learning that if you change the natural disturbance regime, you alter the ecosystem and you may start losing species."

The black-tailed prairie dog's importance to native grasslands, coupled with the dramatic nosedive in the species' numbers, spurred the National Wildlife Federation in 1998 to petition the U.S. Fish and Wildlife Service (FWS) to protect them under the Endangered Species Act. Last February, the FWS ruled that the black-tailed prairie dog was "warranted but precluded" for protection-meaning the animals won't be listed yet, but they will be reevaluated every year. State fish and wildlife agencies, hoping to avoid federal action, have begun to develop their own plans to protect the species.

For many years, human efforts to poison prairie dogs posed the biggest threat to their long-term survival. That threat still looms, but it's now rivaled by another one: plague. "Plague is the largest threat here; others pale by comparison," says Dennis Flath, a biologist with the Montana Department of Fish, Wildlife and Parks. "Plague is an exotic disease, so prairie dogs have no inherent resistance." Without nearby towns to repopulate, plague can turn a colony into a ghost town.