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A Montana State University student has found that bison occupied a large portion of North America beyond the Great Plains region at various points since the Last Glacial Maximum about 20,000 years ago.

John Wendt, a doctoral student in the Department of Earth Sciences in MSU’s College of Letters and Sciences, published the research in a paper titled “Large-scale Climatic Drivers of Bison Distribution and Abundance in North America.”

Wendt wrote the paper with his MSU academic adviser David McWethy, Chris Widga from East Tennessee State University and Brian Shuman from the University of Wyoming. It ran online in the journal Quaternary Science Reviews in April.

The findings show that bison are resilient, and they are capable of adapting to shifting environmental and climatic conditions. When large megafauna, including mammoths and short-faced bears, went extinct between 14,000 and 11,000 years ago, bison persisted.

“This paper really came out of John’s creativity and persistence,” co-author McWethy said in a news release from MSU. “It involved a unique collaboration, and John came up with the idea to reconstruct the spatial distribution of bison across the continent since the Last Glacial period using a dataset that had not been fully explored.”

At MSU, Wendt studies ecology, and he’s especially focused on how ecosystems and environments change over time. He’s mainly interested in herbivores and how they interact with and influence ecosystems.

At the start of the COVID-19 pandemic, Wendt began to toy around with online datasets, using different fossil records. He ended up mapping out bison distribution over time, using data from various archeological sites.

His work sparked interest from other researchers across different fields, including paleontology and paleoclimatology. They tried to piece together a broader picture of how bison herds expanded and contracted across North America over time.

The results reinforce the idea that bison occupied a large portion of the continent at one time, and they reveal that the large mammals responded dynamically to changing temperatures and precipitation levels.

The paper’s co-authors looked as far back as the Last Glacial Maximum — a period when ice sheets were at their greatest extent across North America about 20,000 years ago.

The transition from the Pleistocene era to the Holocene era began roughly 12,000 years ago, when lots of large mammals went extinct, ice sheets melted out, the land bridge disappeared, and humans started to develop agriculture, Wendt said.

During that time of warming, there was a widespread decrease in bison abundance across many regions of the continent, which reached a low point around 4,000 to 6,000 years ago, according to Wendt.

Then, 1,000 to 4,000 years ago, drought conditions eased, moisture availability improved and bison abundance grew.

Written accounts from early white explorers describe vast herds of bison across the plains in the West. That period of time was an unusual one in the continent’s history, and it “was not necessarily representative of prior millennia in North America,” Wendt said.

According to Wendt, the study shows that what those explorers saw was “just the endpoint of a long trajectory of population cycles that played out over thousands of years.” The researchers wanted to understand the deeper history of bison in North America.

Wendt said he benefitted from the work of “thousands of archeologists, paleontologists and scientists” who have gone through the historical record and contributed to different databases — the starting point for the study.

Bison have experienced a range of different climatic conditions, and while they’ve moved in response to some changes, they’ve adapted to extreme conditions — both warm and cold, McWethy said.

That fact bodes well for today’s efforts to reintroduce bison to new areas of the Northern Rockies and Great Plains, which are largely led by tribes. The study shows that bison have been important for those landscapes for many millennia, McWethy said.

“I was really pleased with John taking these ideas and running with them as a Ph.D. student,” he said. “I thought it was really creative and he really persisted, sifting through the data to arrive at really quality analysis.”

“We know that this information can be used by bison managers, people working in bison conservation and restoration, tribes, government agencies, and even people who own private herds,” Wendt said. “We hope this research is useful and informative to them, especially as people work to conserve this iconic species.”

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Helena Dore can be reached at or at 582-2628.

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