The Humboldt marten is a slinky, pet-sized predator that kills porcupines by biting through their faces. With a short nose and the glassy black eyes of a teddy bear, it’s also cute as a button. But the creature’s most impressive characteristic these days may be the saddest: the Humboldt marten is nearly extinct.

There are most likely fewer than 100 alive today, according to federal estimates, and they occupy less than 5% of their original range. Earlier this year, however, the U.S. Fish and Wildlife Service declined to protect the creature under the Endangered Species Act – a move that surprised environmental groups, which have lobbied for years on the marten’s behalf.

RELATED: Why we can stop panicking about the honeybees

Now some of the same groups plan to escalate the battle, suing the U.S. Fish and Wildlife Service for a decision that they say is politically-driven, scientifically-bunk and near-suicidal for the marten.

“Denying protection to the coastal marten is a blatant example of the Fish and Wildlife Service caving to pressure from the timber industry – at the expense of an irreplaceable creature,” Tierra Curry, a senior scientist at the Center for Biological Diversity said in a statement announcing the planned lawsuit.

“The marten needs something,” added Rob DiPerna, the California forest and wildlife advocate for a sister-group known as EPIC, the Environmental Protection Information Center. “We’re pretty confident that we’re going to show that the U.S. Fish and Wildlife Service has erred by making a decision that’s not consistent with their own science and not based on sound reasoning.”

A spokesperson for the Fish and Wildlife Service declined to comment on the lawsuit or the decision against listing the Humboldt marten as an endangered species. But after years of review and re-review there is already a detailed history of the case in the public record.

It began when the Humboldt marten came back from the dead.

The Humboldt marten disappeared in 1947. Hunted for its mink-like fur and chased from its home in the ancient, over-logged forests of Northern California, it wasn’t seen again for decades. Scientists assumed it was gone, destroyed by humanity’s deep cuts into the the state’s coastal forests.

RELATED: Are armadillos the greatest threat to civilization?

And then a sign: the click of a wildlife camera in the Six Rivers National Forrest confirmed that at least one Humboldt marten was still alive. A follow-up survey found dozens more: 60 Humboldt martens in 2000 and 2001. That was followed by a troubling decline to 40 in 2008, with females showing the most substantial decline, according the Fish and Wildlife Service.

“It is likely the entire Humboldt marten population contains fewer than 100 individuals,” the agency concluded in an undated statement on its website.

The Center for Biological Diversity joined the fight in 2010, petitioning the Fish and Wildlife Service to list the marten as threatened. It sued the agency in 2012, after delays in the decision making process. The first step was a 90-day study, which found that the animal “may warrant” protection. That triggered a 12-month review, the results of which were released this spring.

The Pacific marten, which includes coastal Oregon populations of marten and the Humboldt variety, was deemed “not warranted for ESA protections at this time,” according to a statement from the agency. The service evaluated potential “stressors,” including climate change, timber harvests, wild fires, “collision with vehicles” and exposure to rat killer and other pesticides.

RELATED: Could elephants become extinct in near future?

None of these stressors, the Fish and Wildlife Service concluded, “rise to the level of a threat either individually or cumulatively.”

Greg Loarie is an attorney for EarthJustice, a nonprofit law firm that’s preparing the filing against the agency. He told MSNBC that the 90-day Fish and Wildlife Service report seemed to strongly support listing the marten, but some of the findings were “inexplicably reversed” in the final report – a change he can’t help by attribute to politics, not science.

“In the end,” he and his colleagues wrote in the notice to sue filed this month, “it is apparent that the Service’s 12-month finding is not based solely on the basis of the best scientific and commercial data available, but rather is arbitrary and capricious.”

The Fish and Wildlife Service has 60 days to respond before the lawsuit itself is filed in November.