Ancient Bison Hunters Deserted Long-Occupied Site 1,100 Years Ago in Response to Climate Change

On the expansive Great Plains of North America, the American bison once roamed in vast numbers, forming a cornerstone of the indigenous peoples’ subsistence and culture for thousands of years. Archaeological evidence reveals that bison were hunted consistently across millennia, employing diverse hunting strategies and various types of kill sites that shifted according to both ecological and social factors. Yet the story of bison hunting is not only one of relentless pursuit but also of discernible shifts in site use and eventual abandonment, even while bison populations persisted in the surrounding landscape.

A recent scientific investigation, published in Frontiers in Conservation Science, sheds new light on why certain bison kill sites fell into disuse despite the continued presence of bison herds nearby. Centered on the Bergstrom site in central Montana, an archaeological locale actively utilized for approximately 700 years, the study explores why hunters ceased visiting the site around 1,100 years ago. Dr. John Wendt, the study’s lead author and paleoecologist at New Mexico State University, explains that environmental stressors, particularly severe, recurring droughts, constrained water availability critical for processing large game. These climatic challenges intersected with shifting socio-economic dynamics, prompting hunters to abandon a site that had once been highly productive.

The multidisciplinary research team employed an integrative approach, combining detailed archaeological excavation with paleoenvironmental reconstructions. In 2019, nine 1×1 meter excavation pits were systematically opened at Bergstrom, with careful documentation and photographic records taken of all materials recovered. Charcoal fragments recovered from sediment layers underwent radiocarbon dating to establish a precise chronology. Simultaneously, sediment cores were extracted adjacent to the excavation area and subjected to palynological and charcoal analyses, further elucidating past vegetation patterns and fire regimes. Supplementing this, data on large herbivore populations and regional climatic reconstructions were synthesized to discern possible ecological or anthropogenic causes behind the site’s abandonment.

Intriguingly, the analyses indicated that ecological factors, such as bison abundance and vegetation composition, remained largely stable across the period leading to site abandonment. The sporadic fire activity and steady presence of herbivores suggested that ecological degradation was not the primary driver for deserting Bergstrom. Instead, the research underscores that hunter activity did not directly mirror prey availability; rather, external factors influenced settlement and hunting strategies.

A critical discovery was the role of prolonged drought episodes, which profoundly affected the hydrological landscape. Limited water resources, especially at the small creek near Bergstrom crucial for processing carcasses and sustaining winter activities, rendered the site vulnerable amid climate stressors stretching over several decades. This scarcity substantially reduced the site’s attractiveness for repeated occupation and large-scale operations, forcing hunter groups to reconsider their spatial strategies.

Concurrently, the study notes a significant sociological shift in hunting group dynamics. Earlier, small, mobile bands hunted opportunistically, adapting swiftly to local conditions. Over time, these bands coalesced into larger, more coordinated groups undertaking complex, infrastructure-supported hunts. Such larger operations favored extensive bison kills, generating surplus meat that could be stored or traded, but also necessitated stable, resource-rich locations. Reliance on reliable water sources, abundant forage for herd maintenance, and fuel for processing fires became paramount.

The geomorphological attributes of ideal hunting sites further restricted options. Large-scale bison drives required specific topographical features such as cliffs and natural enclosures conducive to directing herds. Sites fulfilling these criteria were rare but could support intensive, repeated use spanning centuries. Hence, hunters’ strategic consolidation around fewer, more suitable sites was a form of cultural adaptation aimed at maximizing returns under changing environmental and social contexts.

This cultural flexibility, emphasizing the maintenance of institutional knowledge and the capacity to restructure hunting practices, was instrumental in the long-term persistence of bison hunting traditions despite climatic variability. The Bergstrom site exemplifies such sophisticated adaptation; although eventually abandoned, it reflects broader patterns of human resilience and dynamic response to environmental constraints. Enduring drought conditions necessitated relocation and innovation rather than simple cessation of bison exploitation.

Importantly, the study cautions against broad generalizations. While the Bergstrom site abandonment was linked to drought and socio-economic restructuring, other bison kill sites in the region could have different histories influenced by alternate forces. Moreover, the research acknowledges limitations in resolving the duration and frequency of site use over the 700-year period, as well as the possibility of subtle, intermittent utilization leaving minimal archeological traces.

This nuanced understanding of late Holocene bison hunting sheds light on prehistoric human-environment interactions and emphasizes that ecosystem stability does not preclude dramatic shifts in cultural practices. The research contributes crucial knowledge relevant for contemporary bison management, suggesting that flexible, adaptive strategies may enhance resilience amid ongoing and future climate variability.

Dr. Wendt concludes that the story of Bergstrom echoes a larger narrative: “While humans have navigated climate challenges for millennia, the last 2,000 years demonstrate how communities reorganized in response to recurring droughts, underscoring the continuous interplay between environment, culture, and subsistence.”

The findings not only enrich archaeological and ecological discourse but also provide valuable insights for modern conservation efforts, highlighting that sustainable management of wildlife resources benefits from preserving cultural adaptability and system flexibility in the face of environmental uncertainty.