A U.S. Fish and Wildlife Service official has ordered federal biologists to withdraw their conclusion that the last 300 wolverines in the continental United States deserve threatened species status.
The biologists had recommended the protection on grounds that climate change is destined to destroy the near-arctic conditions of the remaining animals' habitat — even though the population of about 300 has shown signs of slight growth in recent years.
Officials in three states where most of the animals are still found — Wyoming, Montana and Idaho — vigorously objected. They argued that conclusions about the effects climate change will have on wolverine habitat are premature.
The states also warned that safeguarding the animals could have dire economic effects on recreational activities, development and trapping on large swaths of alpine terrain already locally managed for wolverines in their states.
Noreen Walsh, a biologist and Fish and Wildlife director for the region that includes Wyoming and Montana, initially praised the biologists' recommendation after it was issued in early 2013.
But the three states then raised questions about the degree to which wolverines are dependent on deep snow in the spring for security and a thermal buffer for kits. The states also were skeptical that scientists could accurately measure the impact of warming temperatures on wolverine behavior and habitat.
In response, the agency asked a panel of nine biologists to reevaluate the scientific information. The panel concluded in April that wolverines would continue to expand their ranges in the near-term, but that by the end of the century, populations would likely be significantly affected by habitat loss due to climate change.
Based on those findings, Terry Rabot, assistant director of ecological services in the Pacific region, proposed that the agency proceed with the process of granting threatened status for the wolverine.
That recommendation came even though biologists had yet to document the current effect of climate change on wolverines, as has been done with other animals. For example, scientists have documented drownings of polar bears that lacked the endurance to swim from retreating ice packs to shore.
For wolverines, however, detecting a response "either now or in the future is unlikely due to the near impossibility of obtaining such information on this hard-to-study species," Rabot said.
A listing as threatened under the Endangered Species Act would protect U.S. wolverines as a population segment geographically separated from those in Canada and Alaska. (There are scattered populations of wolverines, the largest member of the weasel family, beyond Wyoming, Montana and Idaho; a lone wolverine was spotted in California in recent years.)
Walsh ordered a reversal of the recommendation to list the animals as threatened, the agency confirmed Thursday. She cited uncertainties "about the degree to which we can reliably predict impacts to wolverine populations from climate change," according to agency documents obtained by The Times.
Gavin Shire, a spokesman for the agency, said Walsh's memo "reflects one step in an objective and deliberative internal process" regarding the status of the wolverines.
Critics accused Walsh of injecting politics into a scientific process.
Jeff Copeland, a spokesman for the nonprofit Wolverine Foundation and a retired U.S. Forest Service biologist, said that for Walsh to reverse the recommendation "without any new scientific evidence is a sign of strong political pressure from the states."
Noah Greenwald, director of endangered species at the Center for Biological Diversity, said, "Caving to political pressure from the states goes against repeated pledges by the Obama administration to let science rule the day when it comes to decisions about survival of our most endangered wildlife."
Fish and Wildlife Director Dan Ashe is expected to make a final determination on the matter by Aug. 4.