portion of remaining 'pure' bison in Yellowstone
By SCOTT McMILLION Chronicle Staff Writer
of the bison herds in the country include animals that
are part beef cow, new research by a Texas geneticist
has found, but the bison in Yellowstone National Park
are the pure stuff.
"A whole lot of bison out there have cattle genes,"
said Dr. James Derr, a geneticist at the Texas A&M
College of Veterinary Medicine.
Approximately 300,000 bison live in North America, a vast
improvement from the handful of animals that survived
in the 1890s after the slaughters of the 19th century.
However, most of those bison herds include animals that
carry genes from domestic cattle, the residue of crossbreeding
experiments that continue today.
Only about 15,000 animals live in herds that Derr has
found to be genetically pure.
They include the Yellowstone herd and herds in Grand Teton,
Badlands, Theodore Roosevelt and Wind Cave national parks,
along with a few private herds.
The Yellowstone herd is genetically robust, healthy and
diverse, Derr said Tuesday in a telephone interview.
With 15,000 animals, bison recovery "is still a pretty
good success story," he said. "They certainly
aren't an endangered or threatened herd any more."
At least one person maintains otherwise.
James Horsley, of Moorhead, Minn., petitioned the U.S.
Fish and Wildlife Service in 1999 to list the Yellowstone
bison as endangered.
He maintained the bison there are unique because, unlike
other herds in the country, they are allowed to roam unfenced.
The USFWS has taken no action on Horsley's petition because
it has no money or time to do so, said Chuck Davis, endangered
species listing coordinator in Denver.
Doug Honnold, an attorney with Earthjustice Legal Foundation
in Bozeman, has sued the government over Endangered Species
Act issues several times.
He said Tuesday he had never considered doing so over
bison, but agreed the news of the unusual genetic purity
in the park animals could add a new wrinkle to bison debates.
In a recent court decision, a federal judge said "you
can't slop together the hybrids with the purebreds,"
when it comes to recovery westslope cutthroat trout, Honnold
But bison aren't trout, which crossbreed eagerly.
To crossbreed a bison and a beef cow "you have to
force the issue," Derr said. "You have to pen
them up together and make it happen."
Still, people have been doing exactly that for a long
time, hoping to breed a heartier range cow. Male offspring
of those unions are sterile, but females are fertile.
Bison with some cattle genes look like cattle, and for
many owners of private herds, having a less-than-pure
beast makes no difference.
Derr said his team has tested at least 3,000 bison by
analyzing hair follicles and that he was surprised at
the number of hybrids he found.
In some private herds, all the animals are hybrids, he
said, but most contain between 5 percent and 10 percent
While he said his findings would not justify ESA protections
for bison, Derr said they do spell out the uniqueness
of the Yellowstone herd, which contained fewer than 25
animals 100 years ago.
That herd rebounded and animals from the park served as
seed stock for herds all over North America.
The Park Service has a duty to maintain the genetic purity
of the herds in Yellowstone and the other parks, he said.
So far, they've been successful enough that every year
excess animals are sold in other parks or slaughtered
outside Yellowstone for disease control.
"They outgrow their boundaries every year,"
he said. "Those herds are healthy. We're not in any
danger of losing them."
There are about 3,400 bison in the park now. Management
guidelines say the target population is about 3,000 animals.