The Joseph H. Williams Tallgrass Prairie Preserve, expands across the vast landscape just north of Pawhuska. The almost 40,000-acre conservation area is one of the few remaining places where American Bison are free to roam. Except once per year.

Every fall, Preserve Manager Bob Hamilton and his crew of dedicated ranch hands head out on the world’s largest protected remnant of tallgrass prairie to round up over 2,500 bison for the annual gathering of the herd for health maintenance, weighing, vaccinations and ecological sustainability.

“It really starts a couple of weeks ahead of time,” Hamilton said on Friday. “Typically, right after Columbus Day, our guys will start pulling the animals, or sooking them from a feed truck to get them out of the 24,000-acre area.”

The annual roundup, now in its 24th year, is a process that takes days to complete. From sunup to sundown, a steady crew works with the wild bison, a stubborn and temperamental beast that does not deal well with human interaction.

Hamilton and his men work steadily and are just as stubborn as the bison they are rounding up.

“It really is a long process, but we do it to make sure our herd and our land is taken care of in the best possible way,” Hamilton said. “After we begin the process of getting the bison off the entire 24,000-acre area, we pull them in to sequentially smaller and smaller pastures, until ultimately we get them into about 200 acres right here next to the corrals.”

Once that monumental task is complete, the ranch hands and borrowed cowboys use trucks to push approximately 600 bison into the corrals each morning.

“Over the years we’ve learned it’s a little easier to push than pull them with candy (feed cubes),” Hamilton said.

When the grumpy bison are finally corralled, the herd is meticulously placed into a sweep tub where they go through a series of gate locks. At the end of the process, each bison is weighed, the sex is determined and if it is a cow, a pregnancy check is completed.

After receiving vaccinations and other medication, the fate of the bison is determined. Hamilton said either they are kept on the preserve, or they are declared surplus and will be sold to a buyer.

“We pull off the surplus animals to maintain the ecological sustainability of the preserve,” Hamilton said.

All throughout the annual gathering, a count of the herd is completed. The ideal number for the preserve is approximately 2,500 bison.

“We wont know how many calves we’ve had this spring until we count noses this week,” Hamilton said. “But I would expect around 2,700 in the number of bison that we’ll touch.”

The Joseph E. Williams Tallgrass Preserve was established in 1989 by the nonprofit group, the Nature Conservancy. In 1993, Bartlesville rancher Kenneth Adams donated 300 bison to roam free on the preserve. Since then, the herd has grown to its current size.

According to the Nature Conservancy’s website, bull bison are sold at 6-7 years of age, since after this they tend to become more aggressive and dangerous. Cows are sold at 10-12 years of age. They are still productive through their early 20s but their sale value is higher as teenagers. Also, the older cows are less physically fit for withstanding the rigors of roundup.

The herd receives no supplemental feeding, but, because the animals are in a restricted range, salt with trace minerals is provided. Water is available in creeks and ponds.