The Next Great Hunt

The Great Hunt of the late 1800s nearly drove bison to extinction. Now, a new kind of hunt may be the only way to save them.

By Jim Robbins

But the US government viewed the enormous herbivores, a staple for many Native American tribes, as a barrier to western colonization. So it launched the Great Hunt. Bison were hunted out of existence all across the southern Plains by the 1870s.

By 1880, railroads had pushed into the Northwest, and the hunters set to work wiping out bison in Montana, Wyoming, and the western Dakotas. In 1882, Montana and the Dakotas shipped 200,000 hides to tanneries in the East. By 1884, just 300 hides were collected.

Tens of millions of bison had been reduced to fewer than 1,000, and the species teetered on the precipice of extinction. About two dozen were hanging on in Yellowstone National Park, and another 250 survived in Wood Buffalo National Park in Canada.

Some of the cattle ranchers who owned the rest hypothesized that a cross between native bison and Asian cattle would make a more disease-resistant animal. They began breeding the two species to produce a cross they called cattalo, which has proven over time to be a less robust animal than either of its ancestors.

Today, many US bison are descendents of the original cattalo, which agencies and individuals used to restore herds across the country. As a result, the vast majority of bison have a smattering of cattle in the family tree. The few remnant populations of pure bison are scattered, from Ted Turner’s Vermejo ranch in New Mexico to Wind Cave National Park, where the American Prairie Foundation’s bison originated. But the extent of the phenomenon was unknown until efforts got underway to restore the Great Plains.


Bison testing, like that done on the American Prairie Foundation preserve, continues to yield surprising results. In September, DNA analysis conducted by Derr confirmed that the bison of California’s Santa Catalina Island, long thought to be purer than those on the mainland because they have lived in isolation since the 1920s, are hybrids. A microscopic pinch of cattle genes might seem unimportant, but it could result in the extinction of the North American bison. Even if thousands of bison remain, if they all have a sprinkling of cattle genes, there would be no pure bison genome—they would become what biologists call “genomically extinct.”

While some might argue that it’s a question of semantics, the missing bison genes in the hybrids could have a real impact on the species. “You can’t see any difference visually” between bison that have the cattle genes and those that don’t, says Kyran Kunkel, a World Wildlife Fund biologist who works with the American Prairie Foundation. “But we don’t know what the long-term ecological or biological impacts would be.” Scientists do have a few guesses, though. They know that crossbreeding has led to less fit animals, rather than the desired  “hybrid vigor.” The missing genes could affect the ability to digest certain plants or resist a disease, says Freese. “If cow genes became too common in the mitochondria of the cell, which affects metabolism, they could affect the adaptation to cold weather,” said Freese.

Bison are threatened in other ways. Biologists say bison are in effect “ecologically extinct” because they no longer act in their former ecological role—migrating long distances, for example, or gathering in huge herds. That means that even if large numbers of the purest bison are restored to giant swaths of prairie, old behaviors might be absent, lost through generations. If restored bison don’t roam in massive herds, nourishing the ecosystem, it could make the restoration of the Plains incomplete.

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