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Associated Press

BOZEMAN (AP) - Genetically speaking, bison in Yellowstone National Park are the pure stuff, a Texas geneticist says.

But most of the rest of the bison in North America are part beef cow, said Dr. James Derr of the Texas A&M College of Veterinary Medicine.

"A whole lot of bison out there have cattle genes," he said.

Of the estimated 300,000 bison living in North America, only about 15,000 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 especially robust, healthy and diverse, Derr told the Bozeman Daily Chronicle in a telephone interview Tuesday.

Bison recovery from the handful of animals that survived the slaughter of the 19th century, even with just 15,000 of them considered pure, "is still a pretty good success story.

"They certainly aren't an endangered or threatened herd any more," he said.

James Horsley, of Moorhead, Minn., disagrees and petitioned the U.S. Fish and Wildlife Service in 1999 to list the Yellowstone bison as endangered. He maintained the Yellowstone bison 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.

Derr said the reason most North American bison are not genetically pure is continuing crossbreeding in attempts to breed a healthier cow.

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."

Male offspring of those unions are sterile, but females are fertile.

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 hybrids.

He said his findings would not justify federal protections for bison but further 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 National Park Service has a duty to maintain the genetic purity of the herds in Yellowstone and the other parks, he said. And 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.

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