The U.S. Fish and Wildlife Service has denied a request to offer added protection to black-footed ferrets at reintroduction sites in Arizona, Wyoming and South Dakota.

The request, filed by Denver-based WildEarth Guardians, had asked for higher levels of protection for ferrets at the reintroduction sites.

In a statement, FWS said the rules in place "achieve an appropriate level of regulatory protection."

The animals at the reintroduction sites carry a "nonessential experimental designation," which allows for more flexibility on the part of the federal wildlife agency and its partners in the effort to re-establish ferrets.

Guardians had asked FWS to change that status to either endangered or essential where they occur on public land.

The nonessential experimental designation is the same as that applied to the reintroduction efforts in Logan County. That site was not included on the request by WildEarth Guardians.

In its statement, FWS said simply filing the petition had a detrimental effect on black-footed ferret recovery.

"Shortly after the petition was filed, a Wyoming landowner -- citing concerns about potential legal liability -- decided not to proceed with an introduction on one of the largest sites suitable for reintroduction in the species' range," the statement said.

"We have denied this petition because the threats that were cited are minor issues that lack supporting documentation and are unlikely to cause population level impacts to ferrets," FWS regional director Steve Guertin said.