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Are Bison An Endangered Species? Fish And Wildlife Service Says No, Courts Say Not So Fast


A federal judge has directed the U.S. Fish and Wildlife Service to reexamine the question of whether Yellowstone National Park's bison herds need Endangered Species Act protection/NPS

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 National Park's bison are genetically pure, you might think otherwise. While the U.S. Fish and Wildlife Service has ruled that Yellowstone bison don't need protection of the Endangered Species Act, a federal judge isn't so sure.

In his ruling this week, U.S. District Judge Christopher R. Cooper held that the Fish and Wildlife Service didn't adequately refute evidence provided by the Buffalo Field Campaign and Western Watersheds Project that the genetic purity of Yellowstone's bison is threatened by disease, hunting, habitat loss, mismanagement, and the risk of the introduction of cattle genes into their population.

"The Service argues that ultimately, Buffalo Field’s concern over the (park's) two subpopulations is irrelevant because the bison population is growing," wrote Judge Cooper. "The Service may have a point, and on remand the Service may well be able to reach the same outcome after applying the proper standard. But to do so, the Service must explain why the evidence supporting the petition is unreliable, irrelevant, or otherwise unreasonable to credit rather than simply pick and choose between contradictory scientific studies."

To better understand this case, a little history is necessary. 

In 1870, it’s 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 bison are believed to be genetically pure because they descended from pocket herds that escaped the great slaughter of the late 19th century because 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 U.S. 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 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 December 2015, the Fish and Wildlife Service after a 90-day review period denied this petition, and a second one that argued much the same points. In its decision document, the agency said that "maintenance of the two distinct populations (in Yellowstone) might not be crucial for the survival of the species," the judge's ruling noted.

In their lawsuit challenging the Fish and Wildlife Service's finding, the Buffalo Field Campaign and Western Watersheds Project argued that the agency's ruling was arbitrary and capricious under the federal Administrative Procedures Act "because the Service ignored the plain language of the Endangered Specis Act, failed to follow the requirement to make decisions based on the best scientific and commercial data available, and applied an improper evidentiary standard."

Judge Cooper, who held a hearing on the matter on January 18, agreed. Citing two opposing scientific positions on the question of whether the central and northern bison herds in Yellowstone are separate, the judge wrote that "if reasonable scientists disagree -- and one of those positions would indicate listing is warranted -- a reasonable person could choose to agree with the scientist who supports the petition and, as a result, that listing may be warranted.

"At the hearing, the Service did not contest that this is the proper standard for a 90-day hearing," he wrote. "It naturally follows that the 90-day standard does not allow the Service to simply discount scientific studies that support the petition or to resolve reasonable extant scientific disputes against the petition. Unless the Service explains why the scientific studies that the petition cites are unreliable, irrelevant, or otherwise unreasonable to credit, the Service must credit the evidence presented."

Digging down into a study by Dr. Natalie Halbert that theorized that the two herds are genetically distinct, Judge Cooper wrote that the IBMP's population goal of 3,000 bison in Yellowstone could be too low.

"Since other studies have suggested that around 3,000 bison are needed to ensure a herd’s survival, this suggests that the 3,000 bison population target for both herds is too low to ensure that each herd will survive," he noted.

While Judge Cooper agreed the Service's expertise in wildlife issues should carry the day when weighing evidence backing a listing petition, "the Service made no such conclusions here: it offered no explanation whatsoever for its rejection of the Halbert study."

"Ultimately, the Service simply picked a side in an ongoing debate in the scientific community, which is improper at the 90-day finding stage," the judge held.

Michael Harris, director of the Wildlife Law Program for Friends of Animals who argued the case against the government, said Thursday that the Fish and Wildlife Service could respond by reissuing its 90-day finding that Dr. Halbert's position is wrong. But he predicted that the agency is more likely to conduct a year-long review.

“I don’t think anyone questions her research. I just think some people dispute it," he said during a phone call from his Denver office. "I think the people that even dispute Dr. Halbert would raise an eyebrow if the Fish and Wildlife said this was obsolete, unsubstantiated.”

Buffalo Field Campaign Executive Director Ken Cole calling the judge's ruling "a huge victory," adding that, “(T)his is a long battle but we won a significant round for the buffalo today.”

At the Western Watersheds Project, officials said the Fish and Wildlife Service's finding was politically driven.

“The Fish and Wildlife Service made a political decision to suppress and ignore science in order to deny the Yellowstone bison the protection they deserve,” said Josh Osher, Montana director for the organization. “The administration is clearly bowing to the influence of the livestock industry and its agenda to minimize bison populations and their natural migrations, despite their status as the national mammal.”

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Your story unfortunately containsa factual error on genetic purity, and some misleading statements on bison management.

First: genetic purity cannot be definitively proven. This is an evolving field of science, with new technology regularly emerging. Even geneticists avoid using the term "puriity," because new developments are always arising.

Second: Even based on the current understanding of genetic integrity, Yellowstone bison are not alone in showing the lack of cattle genetic introgression. Even within the National park System, the bison herd at Wind Cave has been tested and shown to be free of cattle genetic introgressions. Many private ranchers are actively testing their herds, and culling those animals that show signifcant degress of cattle introgression.


Third: The issue of cattle genetics in bison must be put into historical context. Those genetics were introduced about 130 years ago, when some of the handful of ranchers who saved bison from extinction briefly experimentd with crossbreeding in an attempt to create a winter-hardy hybrid. Those experiments failed, and the practice soon ended. Those legacy cattle genetics comprise less than 1.5 percent of the genetic makeup of modern bison that descended from those herds. The National Bison Association's Code of Ethics prohibits crossbreeding of bison with other species, and--as stated aboe--many ranchers are testing their animals to address that legacy issue.

Dave, thanks for weighing in on this issue. I did raise the question of Wind Cave's bison herd with Mr. Harris, and he didn't want to go down that road, and pointed out that the lawsuit was focused on Yellowstone, and the filing maintains that Yellowstone's bison herd(s) is the only one without cattle-gene introgression.

I've raised that issue with Wind Cave officials in the past, and while they claim that there is no cattle-gene introgression with their herd, officially, apparently a test by American Prairie Reserve raised some question about that point.

And then there's the issue of nucleic DNA vs. mitochondrial DNA and and how they are passed on (males can't pass on mitochondrial DNA) and the traits they might display in offspring.

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