33 Years After Ranchers Donated 300 Bison to a Struggling Prairie, the Herd Has Grown to More Than 2,500

**Bison Population Flourishes at Oklahoma’s Tallgrass Prairie Preserve**

The Joseph H. Williams Tallgrass Prairie Preserve in Oklahoma is witnessing a remarkable ecological revival, thanks largely to the diligent efforts of conservationists and the reintroduction of bison into the area. In 1993, local ranchers Kenneth and Dianna Adams made a significant contribution by donating 300 bison to the prairie, which has since flourished to a population exceeding 2,500. This initiative has been closely monitored by The Nature Conservancy, whose goal is to enhance biodiversity in this vital landscape.

The original herd, now known as the Christina Adams Bison Herd in tribute to the Adams’ daughter, plays an essential role in maintaining the health of the approximately 40,000-acre preserve located north of Pawhuska, about 55 miles northwest of Tulsa. This area is noted for being the largest remaining remnant of tallgrass prairie globally, an ecosystem that has suffered severe losses over the years.

Historically, bison once roamed in vast numbers across North America, with estimates suggesting their population may have ranged from 30 to 60 million in the Great Plains. However, by the end of the 19th century, this majestic creature was nearing extinction due to over-hunting and habitat destruction, with fewer than 1,000 remaining. Tragically, the tallgrass prairie that supported these herds also faced dramatic declines, now reduced to less than ten per cent of its original expanse, according to data from the Oklahoma Historical Society.

Efforts to conserve the tallgrass prairie gained momentum in Oklahoma during the 1970s, culminating in the establishment of the Nature Conservancy-operated preserve in 1991. The acquisition of approximately 30,000 acres of the Chapman-Barnard Ranch in 1989 enabled advocates to safeguard this vital habitat.

Bison have become crucial to the ecological balance of the prairie through their grazing behaviour. They primarily consume grasses, thereby allowing the space and resources necessary for a variety of broadleaf plants, typically referred to as forbs, to flourish. This increased plant diversity is vital for sustaining a broader range of animal species. Harvey Payne, the community relations coordinator at the preserve, explained that the introduction of cattle grazing has substantially shifted the balance of plant communities over the past century, resulting in a decline of forbs and, consequently, animal diversity.

With the bison population now thriving, tracking their health and maintaining its growth has become an annual responsibility. Each autumn, staff from the preserve and local wranglers conduct a meticulous roundup to monitor the herd’s well-being, which includes health assessments, vaccinations, and weight measurements. During the most recent roundup in 2025, the population was recorded at 2,025, which included 486 calves born that year, demonstrating the herd’s continuing expansion.

However, the logistics of the roundup are no small feat. The bison roam freely across about 23,000 acres, rendering the task of gathering them intricate and demanding. Wranglers employ cattle cubes, a type of feed, to gradually funnel the animals into smaller pastures before closing gates behind them. This technique requires both strategy and patience, ensuring that each step is executed without causing undue stress to the animals.

Once the bison are successfully herded into corrals, they move through increasingly narrower passageways into a working chute for examination. Each bison is identified by a unique ear-tag transponder, allowing the team to keep detailed records of an individual’s age, weight, and health status. This systematic approach is essential for monitoring the overall welfare of the herd.

Despite the effectiveness of these methods, Payne acknowledged the challenges that come with herding the bison, especially from the larger pastures. “The bison are aware of the roundup and tend not to cooperate,” he explained. The wranglers often find themselves faced with the difficulty of persuading the animals to move towards their destination, echoing historic hunting practices where bison were once driven to manage their populations.

The revitalisation of Oklahoma’s tallgrass prairie through the reintroduction of bison truly marks a significant milestone for conservation efforts in the region. As the herd flourishes, so does the diverse ecosystem that depends on it, providing hope for the restoration of a crucial landscape that has endured many challenges in the past.