A Ferret Comeback

In September 1981, a dog named Shep was patrolling a ranch in Meeteetse, Wyoming, when he came across a black-footed ferret (BFF). They scuffled; Shep killed it. Even so, the encounter was good news—because everyone had thought that BFFs were extinct. Shep’s kill changed the course of the species’ existence.

The BFF is a member of the weasel family. Active at night, it eats mostly prairie dogs. After killing a prairie dog, a BFF steals its burrow. The ferrets are “highly effective predators,” says Ryan Moehring, a spokesman for the U.S. Fish and Wildlife Service (FWS).

More than 100 years ago, BFFs roamed the prairies of North ­America by the tens of thousands. By the 20th century, the animals were twice thought to be extinct. But the BFF Shep killed proved once again that the critters are still around.

After Shep’s discovery, FWS researchers scoured the area and found a colony of the ferrets near the ranch. But by 1986, only 18 were left in the wild. In an effort to save the species, the scientists scooped up those 18 BFFs and started breeding them in captivity.

Today, thanks to this effort, about 300 of the ferrets are back in the wild across the Great Plains and Rocky Mountains (see map, below). Another 300 or so remain in captivity for breeding. Still, the BFF remains on the endangered species list.

Many factors contributed to the BFF’s decline. Humans have been developing the species’ prairie habitat. The BFF’s main food source, prairie dogs, is also dwindling because of habitat loss, unpop­u­larity with ranchers, and a disease called sylvatic plague.

Sylvatic plague is caused by the same bacteria responsible for the bubonic plague, which killed one-third of Europe’s human population during the ­Middle Ages.

It is just as deadly, if not more so, in prairie dogs and BFFs. Fleas carry the bacteria that cause sylvatic plague. When infectious fleas bite a prairie dog or BFF, they pass along the disease, which is usually fatal.

Because prairie dogs are key to the survival of BFFs, it’s important to help them fight sylvatic plague. That’s easier said than done. Prairie dogs live in connected burrows that form larger networks called prairie dog towns. These extend across very large areas, which makes reaching wild prairie dogs difficult.

At first, FWS biologists killed fleas by searching for burrow entrances, then spraying insecticide into them. “It’s a very time- and cost-intensive endeavor,” says Moehring.

Now scientists are trying a different disease-fighting tool: vaccination. Vaccines allow a body’s immune system to build defenses against a specific disease. But this vaccine isn’t injected; it’s an edible ­peanut-butter-flavored pellet.

The vaccine has worked well in trials, and the FWS is testing ways to get it to wild prairie dogs. One way is to deposit pellets near prairie dog towns using all-terrain vehicles. Another is to deliver the pellets using drones.

“We believe we are going to be successful,” says Moehring. Still, saving the BFF will require efforts from government and conservation organizations, as well as everyone who lives in areas where the animal once thrived. Private landowners are some of the best partners the government has to help reintroduce and save the species, Moehring notes.

“We have all these amazing creatures here in North America in people’s backyards,” he says. “Animals like the black-footed ferret are part of our American heritage; they’re part of us.”