But sylvatic plague, known as the bubonic plague in humans has killed off prairie dogs on thousands of acres in the region since the early 1990s. The plague, which is spread by fleas and hard to predict, struck again this year on the Fort Belknap Indian Reservation in northern Montana, another reintroduction site. Some, wildlife officials say the plague is not the only culprit. They contend management of public lands that has permitted sometimes advocated - the shooting of prairie dogs has compounded the losses. For years, the sport shooting of prairie dogs has been widely accepted in Montana and other areas where the animals thrive.
Defenders say the prairie dog shoots are a valuable control method.
But environmentalists have become more vocal in calling for an end to the sport after learning that the ferrets were being reintroduced into prairie dog areas. The BLM, which for years permitted prairie dog shooting on its land, has changed its policy. The agency imposed a mandatory ban late last year on 15 prairie dog towns where ferret reintroduction efforts are under way or planned. John Grensten, a wildlife biologist for BLM, said the agency is trying hard to juggle its responsibility to protect the ferret and its requirement, to allow public access to the land. It has not been easy.