Yellowstone bison near Frying Pan Springs/NPS, Jacob W. Frank

Yellowstone National Park bison will not be reviewed by the U.S. Fish and Wildlife Service for Endangered Species Act protection, as the agency doesn't believe there is evidence the species needs it.

In a brief statement placed in the Federal Register on Friday, the Service said, "the petitions do not present substantial scientific or commercial information indicating the petitioned action may be warranted for Yellowstone National Park bison. Because the petitions do not present substantial information indicating that listing Yellowstone National Park bison may be warranted, we are not initiating a status review of this species in response to the petitions."

However, the agency said it welcomed any additional new information that indicates Yellowstone's bison need ESA protections.

This is the second time the agency declined to consider the park's bison for listing under the ESA. The last time it did so a federal judge said the agency didn't adequately refute evidence that the genetic purity of Yellowstone's bison is at risk from disease, hunting, habitat loss, mismanagement, and the risk of the introduction of cattle genes into their population.

“Once again, the U.S. Fish & Wildlife Service has applied the wrong evidentiary standard in our petition to list the Yellowstone bison as threatened or endangered,” Darrell Geist, of the Buffalo Field Campaign that previously sued the agency over bison listing, said Friday after the Register posting came out. “The genetically distinct subpopulation of wild bison in the Central range is at risk of extinction. Nothing is being done to turn that fact around.”

With an estimated 500,000 bison across North America, you wouldn't consider that the species is in danger of going extinct. But when you realize a very large majority of those bison have cattle genes in their systems, and that only Yellowstone's bison are believed to be genetically pure, you might think otherwise.

In 1870, it has been estimated, 2 million bison from the “southern herd,” found south of the main east-west railroad line that crossed the Great Plains, were killed. Two years later an average of 5,000 bison a day were being killed. While Yellowstone National Park was established that year, 1872, and its enabling legislation outlawed the wanton destruction of wildlife, there was no one to enforce that regulation until the U.S. Army arrived in 1886 to patrol the park.

By 1876, for all practical purposes, the southern herd was judged to be wiped out, and six years later the northern herd faced the same fate. Extinction for the species loomed in 1902, when, aside from some private herds such as the one Charles Goodnight had established on his Texas ranch, free-roaming bison numbers were thought to be as few as 100, with maybe two dozen in Yellowstone.

Today, Yellowstone's free-roaming bison are believed to be genetically pure because they descended from pocket herds that escaped the great slaughter of the late 19th century as they were secreted away in the upper headwaters of the Yellowstone River deep in the park's interior. Most, if not all, other herds in North America -- most are commercial herds raised for the table -- are thought to carry cattle genes, which were introduced through efforts by Goodnight and Charles "Buffalo" Jones and maybe some others to cross cattle with bison.

Back in 2014, the Buffalo Field Campaign petitioned the Fish and Wildlife Service to extend "threatened" or "endangered" designation under the Endangered Species Act to Yellowstone's bison. In a somewhat lengthy petition of more than 60 pages, the group and the Western Watersheds Project argued that Yellowstone's bison are "the largest remnant population of the Plains bison that ranged across much of United States until it was eliminated post-settlement."

Citing a range of threats, from disease and habitat loss to climate change and accidental introgression of cattle genes, the groups maintained that, "Endangered Species Act protection is necessary to prevent the extinction of the species, and to protect the habitat and the ecosystems upon which Yellowstone bison depend."

But the Fish and Wildlife Service, which is responsible for managing terrestrial Endangered Species Act listings, countered that Yellowstone's bison herds have been growing in number and so don't need ESA protection.

The ageny dismissed climate change concerns, stating that, "bison historically occupied an extensive range (from Canada to Mexico and from the Rockies to Florida to New York) and tolerated a variety of climatic conditions. This suggests YNP bison are likely to be flexible with any climate changes that may occur in the future."

It also questioned how pure Yellowstone bison genes really are.

"(Yellowstone biologists) White and Wallen assert that the observed population substructure and genetic differentiation was 'substantially influenced by a human-induced bottleneck' and as a result, 'there is evidence that the existing genetic substructure was artificially created," it wrote in dismissing the petition. "Since individuals from other herds were used to supplement the YNP bison in 1902, estimates suggest only approximately 30-40 percent of the YNP bison genetic makeup derive from the original 25 survivors. Thus, maintenance of subpopulation genetic differentiation and overall genetic diversity may not be crucial for preserving genes from the survivors of the historic bottleneck."

That point, that there might not be "subpopulation genetic differentiation," is the bone of contention, for the Buffalo Field Campaign and Western Watersheds Project found a study that suggests that Yellowstone's "central" and "northern" bison herds are two separate herds that are "genetically distinct" and so should be preserved.

Key to their argument is that while the Interagency Bison Management Plan adopted in 2000 was established to manage Yellowstone bison, it "was inadequate, in part because it (1) was primarily designed to protect against brucellosis—which, the Petition contends, is not nearly as significant a threat from bison-to-cattle transmission as the IBMP claims—rather than to ensure the survival of the bison, and (2) fails to account for the two distinct genetic herds when setting a population target and thus sets too low a population target to ensure the genetic survival of both herds (and thereby the entire population)."

In reacting to Fish and Wildlife Service's latest dismissal of their request, the conservation groups blamed political pressure for the decision.

“The simple truth is that the livestock industry does not want bison to exist as a native wildlife species in the United States,” said Josh Osher, Montana and Public Policy Director for the Western Watersheds Project. “The Trump administration's latest finding is one more example of way in which industry is favored over the natural world at all costs, even the potential extinction of an American icon, the wild bison.”

Furthermore, they maintain that the finding:

* Wrongly limits the consideration of threats to the bison that occur as a result of the arbitrary confinement of the herds to Yellowstone's boundaries and some small areas immediately adjacent;

* Fails to acknowledge the significant threat posed by climate change to the bison’s current and potential habitat;

* And ignores the fact that the bison herds in Yellowstone are the only remaining wild bison herd of significant size that contain no cattle DNA.  As a wildlife species, bison have lost 99% of their range and been reduced to 1% of their former numbers in North America.