Why an Arizona Rancher Wants to Save the Critically Endangered Black-Footed Ferret

A provision of the Endangered Species Act lets landowners help save imperiled wildlife without restricting use of their property.

(Photo: Rick Wilking/Reuters)

Oct 20, 2014· 2 MIN READ
Hannah Hoag reports on the environment, global health, science, and science policy for Nature, Discover, Wired, and others.

Two dozen critically endangered black-footed ferrets have found a new home on an Arizona cattle ranch.

Normally, ranchers would be loath to welcome one of the United States’ rarest mammals on their property. After all, the presence of a protected critter can trigger all kinds of limits on land use under the federal Endangered Species Act. But under a provision of the law called a Safe Harbor Agreement, landowners who volunteer to conserve an imperiled animal don’t face those restrictions.

Biologists have reintroduced black-footed ferrets at 21 sites in the U.S., Canada, and Mexico in the past 20 years. Five of the U.S. sites were established within the past 12 months under the Safe Harbor Agreement.

“This year has been kind of a banner year with the Safe Harbor Agreement,” said Pete Gober, coordinator at the U.S. Fish and Wildlife Service's National Black-footed Ferret Conservation Center in Carr, Colorado.

Last October, the FWS opened the door for private and tribal landowners to offer up their land for the black-footed ferret.

“Biologically, there is no shortage of sites,” said Gober. “There is a lot of open space that could support prairie dogs and, by extension, black-footed ferrets.”

The ferrets feed primarily on prairie dogs and use their burrows for shelter.

But many farmers and ranchers consider prairie dogs a nuisance because they clip down the grass so that they can keep an eye out for predators. “People are trying to get as much out of their rangeland as possible and prefer to see their grass going to cattle rather than prairie dogs,” Gober said.

Ranchers often shoot or poison prairie dogs when their populations become unwieldy. In 2013, 55 ferrets were released onto Gary Walker’s ranch near Pueblo, Colorado, and helped keep the prairie dog population under control. The Walker ranch was the first private landowner nationwide to participate in a Safe Harbor Agreement for black-footed ferrets.

“A lot of ranchers want to use the black-footed ferret as biological control for prairie dogs,” said Tom Warren, a wildlife biologist, who works with Walker on wildlife and environmental programs on the ranch. Warren said another 26 ferrets were released on the property earlier this year and 25 more will be released this week.

The recent introduction of black-footed ferrets on a cattle ranch near Williams, Arizona, is the first time the animals have been moved onto private land in that state under a Safe Harbor Agreement.

A group of black-footed ferrets had been introduced into the Aubrey Valley near Seligman, Arizona, in 1996. That population is now thought to number about 100 animals. Ferrets disappeared from the area in the 1930s because of the decline of prairie dogs.

The black-footed ferret has been listed as endangered across its entire range since 1967. The loss of native grasslands, eradication of prairie dogs, and novel diseases, including the tick-spread sylvatic plague, have squeezed ferret habitat to 2 percent of its original range.

The recovery guidelines for the black-footed ferret require the establishment of 1,507 breeding adults spread across 256,000 acres in 12 states before the species can be reclassified from endangered to threatened. More than 3,000 breeding adults must become established on more than 512,000 acres before the black-footed ferret can be removed from the endangered species list entirely. Between 275 and 488 breeding adults had been established as of 2013.

“We hope to do half a dozen sites a year for 10 years and get to 100 sites,” said Gober.

Roughly 1,500 acres of black-tailed prairie dog habitat or 3,000 acres of white-tailed or Gunnison’s prairie dog habitat are needed to support a population of at least 30 breeding adult ferrets.

Approximately 3 million acres of land have been enrolled in Safe Harbor Agreements to benefit several species, including the Bay checkerspot butterfly and the valley elderberry longhorn beetle in California, and the Houston toad in Texas.