For thousands of years, people hunted bison across the Great Plains of North America. Ancient hunters in central Montana returned to the same location to hunt for hundreds of years. That suddenly changed around 1,100 years ago when these hunting groups appeared to abandon this site.
While bison still lived in the grasslands and the vegetation patterns remained unchanged, hunters stopped visiting the Bergstrom site, which had been used on and off for generations. New research shows that climate stress, combined with shifting social organization, pushed hunters to rethink their hunting methods.
A new study published in Frontiers in Conservation Science by scientists at New Mexico State University shows a pattern of adaptation rather than ecological collapse.
A Reliable Site Goes Quiet
Researchers decided to investigate the Bergstrom site after noticing that hunters used it on and off for about 700 years before abandoning it, even though bison remained abundant across the region.
“We found that bison hunters ceased using a kill site in central Montana around 1,100 years ago,” said Dr. John Wendt, a paleoecologist at New Mexico State University and the study’s first author. “It appears that hunters stopped using it because severe, recurring droughts reduced the water available for processing animals at a small nearby creek. Site abandonment was a response to environmental stressors and changing social and economic pressures.”
Hunters did not leave the site due to a lack of bison, but because logistical demands for successful hunting had changed.
Digging Into the Climate Record
The team combined archaeological excavation with environmental reconstruction to determine why the site was abandoned. In 2019, they dug nine small excavation units at the site, each measuring one square meter. The researchers documented artifacts, collected charcoal for dating, and took sediment samples from the site.
Scientists then studied pollen and charcoal from the sediment samples, tracked the presence of large herbivores, and compared these findings with regional climate data.
“The Bergstrom site presented a puzzle because it was used intermittently and abandoned when bison were common throughout the region and hunting was intense,” Wendt explained. “Why would hunters stop using a site that had worked for so long?”
The environmental data ruled out a simple ecological explanation. “Abandonment wasn’t because the site became ecologically unsuitable in any absolute sense,” Wendt said. “Bison were still around, vegetation hadn’t changed, and there was no substantive shift in fire activities. Bison hunting activity was not simply following prey populations.”
The climate records indicate that the area experienced long periods of drought both before and after the site’s final abandonment.
Changes in Hunting Operations
Severe drought conditions likely reduced water levels in the nearby creek, making it harder to properly clean and process meat. However, these climate changes alone do not explain the sudden abandonment. The study also points to changes in the social organization of hunting groups.
At this time, many hunting groups transitioned from small, mobile bands to larger, more coordinated groups. They built structures, held large group hunts, and stored extra meat for winter or for trade.
“These larger operations were based on large kills and could produce surplus for trade and winter storage,” Wendt said, “but they also meant more dependence on specific resources like water, forage for larger herds, and fuel for processing fires.”
Certain land features, such as cliffs and natural barriers to keep herds together, were essential for large bison hunts. Reliable water and fuel sources were also important factors for the success of these hunts. Finding a good spot was rare, but once located, hunters returned to it again and again for generations.
Abandonment Through Adaptation
This shift made smaller, water-limited areas like Bergstrom less practical during prolonged droughts. Hunters changed their strategies, focusing on fewer sites that could support larger groups and provide more bison. Under these changing conditions, Bergstrom may have become less attractive than other larger sites with more secure resources.
“While people have been adapting to the climate for much longer, Bergstrom’s abandonment shows that people reorganized in response to recurring droughts in the last 2,000 years,” Wendt concluded.
Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds a Master of Business Administration, a Bachelor of Science in Business Administration, and a Data Analytics certification. His work combines analytical training with a focus on emerging science, aerospace, and astronomical research.