For thousands of years, bison roamed the Great Plains of North America and were an essential resource for indigenous hunters. These hunting traditions continued until the late 1800s, when overhunting brought the bison population to the brink of extinction. But long before its collapse, hunters relied on a variety of strategies and locations to capture bison, sometimes moving from one location to another.
A new study investigated why hunters stopped using a particular site in central Montana known as the Bergstrom Site. Bison were abundant in the area, but the site was used intermittently for about 700 years before it was finally abandoned. The survey results are Frontiers of conservation science.
“We found that bison hunters stopped using hunting grounds in central Montana about 1,100 years ago,” said lead author Dr. John Wendt, a paleoecologist and assistant professor of rangeland ecosystem management at New Mexico State University. “Hunters appear to have stopped using the site due to repeated severe droughts that reduced water availability for processing animals in nearby small streams. Abandonment of the site was a response to changing environmental stressors and social and economic pressures.”
Investigate the mysteries of ancient bison hunting
To determine what influenced hunting decisions at the Bergstrom site, researchers combined archaeological excavations with environmental analysis. Their work included taking sediment cores, conducting laboratory tests, reconstructing climate, and studying past animal and plant activity.
“The Bergstrom site posed a mystery because it had been intermittently used and abandoned during a time when bison were widespread in the area and hunting was active,” Wendt explained. “Why would hunters stop using a site that has worked for so long?”
In spring 2019, the team drilled nine 1 x 1 meter test pits on site. Artifacts and other materials were recorded and photographed, and charcoal samples were submitted for radiocarbon dating. The researchers also collected two sediment cores near the excavation site and analyzed them for pollen and charcoal. Additional data on large herbivores and past climatic conditions helped the team assess whether environmental changes or other factors contributed to the site’s abandonment.
The results ruled out several possible explanations.
“It was not abandoned because the site became ecologically unsuitable in an absolute sense; the bison were still present, the vegetation was unchanged, and there was no substantial change in fire activity,” Wendt noted. “Bison hunting was more than just tracking prey populations.”
Drought and changing hunting strategies
Instead, the evidence pointed to repeated severe droughts that affected the area before and after the site was finally abandoned. These long dry seasons reduced water availability, making locations without reliable water sources less attractive for large-scale hunting operations.
Around the same time, hunting habits were also evolving. Small, mobile groups that hunted opportunistically were increasingly replaced by larger, more coordinated groups. These large-scale operations often relied on built infrastructure and sometimes occupied specific locations for long periods of time.
“These large-scale operations are based on large numbers of catches, which can generate surpluses for trade and winter storage, but also mean increased dependence on specific resources such as water, fodder for large herds, and fuel for firefighting,” Wendt said.
These large-scale hunting operations required more resources, making it harder to find suitable locations. The ideal location needed reliable access to water and other necessities, as well as landscape features that would help move and contain the bison herd. Cliffs and natural barriers used for bison jumping were especially valuable. Once such places were established, they were often used repeatedly over centuries.
Climate adaptation lessons
Large hunting grounds had advantages, but also increased dependence on favorable conditions. These specialized sites are difficult to replace, and hunting groups become even more vulnerable when key resources become scarce.
Researchers believe that long-term success depends on the ability to adapt. Hunting communities passed on knowledge from generation to generation and adjusted their strategies in response to changing environmental conditions. Thanks to their flexibility, the researchers say, these systems were able to withstand periods of climate instability.
This finding may still be relevant today. Modern bison management programs may be able to improve their resilience to changing environmental conditions by maintaining the ability to adjust where and how animals are managed.
Researchers noted that other abandoned bison hunting sites in the area may have been left behind for a variety of reasons. The researchers also stressed that while the study documents approximately 700 years of use at Bergström, it is not possible to determine how long individual periods of occupation lasted or how often the site was used during that time. Additionally, low-impact uses may have occurred from time to time after abandonment, without leaving detectable archaeological evidence.
“Although people have been adapting to climate for much longer, Bergström’s abandonment shows that people have reorganized in response to repeated droughts over the past 2,000 years,” Wendt concluded.
