SALT LAKE CITY (AP) — A secluded group of bison in southeastern Utah is directly descended from bison that once covered the American West, according to new research published Wednesday.
The paper shows the herd could help the recovery of the iconic animals.
The analysis of genetic material by scientists from Utah State and Texas A&M universities shows that the herd of about 350 animals living in the Henry Mountains is free of cattle DNA introduced into the most bison lineages when people tried to breed them with cows in the 19th century.
But cow DNA can alter bison size and behavior, so conservationists want to use bison with the rarer pure genome as the animals are re-introduced to national parks, American Indian lands and private lands from Alaska to Mexico.
"It's important to how these animals look and behave, but also to conservation of the bison genome as a whole," said lead researcher Dustin Ranglack.
The study published in the scientific journal PLOS ONE was done by analyzing cells on strands of hair plucked from the tails of 129 animals, said USU wildlife ecologist Johan du Toit. It was paid for with a grant from the Utah Division of Wildlife Resources.
The Henry Mountains herd is descended from about 20 animals brought to the area in the 1940s from Yellowstone National Park, one of the few other genetically pure lineages.
Over the years, the animals have done well enough there that the state of Utah allows them to be hunted. They now live primarily in an oasis tucked into the red-rock mountains about 250 miles southeast of Salt Lake City, not far from the Butch Cassidy hideout Robbers' Roost canyon.
The free-roaming bison have mingled with cattle from nearby ranches, so it wasn't clear whether the animals had bred themselves with cows over the years.
But the lack of cattle DNA found by the researchers indicates that bison don't breed with cows unless placed with them in confinement, as ranchers did in the 19th century in hopes of creating a crossbreed that would be rugged like a bison, but with a cow's more docile nature.
The study also shows the herd in the Henry Mountains is also free of a bacterial disease called brucellosis that has affected some of the bison at Yellowstone, where the animals number between 3,000 and 5,000.
The new information is important to efforts to bring bison back to parts of their historic range, said Keith Aune, director of the bison programs at the Wildlife Conservation Society.
It's estimated that 30 million to 60 million of the enormous shaggy creatures once roamed North America, but they were hunted to near-extinction in the 1800s and now number more like 20,000 in the wild.
They're being brought back now because they help keep the landscape healthy, said Aune. Their contributions include grazing patterns that help the grasslands stay healthy, shed hair that provides warm, durable material for birds' nests and wallows that fill with water that supports rare plants.
As they relocate bison to form new herds, conservationists pull from lines like the Yellowstone bison that haven't been mixed with cattle DNA.
"That's why the Henry Mountains heard is of high value," Aune said. "It's a great example of a free-ranging herd naturally selected by forces of nature."