Bison Round-Up at Tallgrass Prairie Preserve
Tallgrass Prairie bison are rounded up each fall for their annual checkup.
Harvey Payne glances nervously over his shoulder at more than 2,500 bison which are about to be stampeded. For their own good.
The bison live on The Nature Conservancy’s Tallgrass Prairie Preserve—the largest protected tallgrass prairie remnant left in the world. The Conservancy reintroduced 300 bison (which eat almost entirely grass) here in 1993 to help restore the 39,000-acre preserve's balance between grasses and broadleaf plants.
Now, the entire herd is rounded up every fall by staff and local wranglers for a "check-up"—which includes a weigh-in and vaccinations.
“The wranglers go out and form a wall of pickups and get the bison moving,” Payne explains. “It’s like when the Indians used to drive them over cliffs. Once they get them heading this direction, they come.”
“The bison know what this round-up is all about,” says Payne, the director of the Conservancy’s Tallgrass Prairie Preserve in Oklahoma. “They know what’s going to happen, and they don’t like it."
Round 'Em Up
Payne looks over his shoulder again on this cold, clear November morning, as a faint reverberation of bison hooves pounding the prairie behind him grows louder.
“Here they come,” Payne says as a herd of about 300 rumbles past him. Wranglers standing on the backs of flatbed pickup trucks are hollering and the drivers are revving their engines to discourage the bison from turning around and exiting a holding pen corral before the gates close.
Cattle cubes (or feed bait) are used to entice the bison—which roam freely on 23,000 acres at the preserve — into progressively smaller pastures, each time closing gates behind the animals.
“It's a difficult job,” Payne says. “Our guys had a lot of trouble getting the bison from the last 1,500-acre pasture into these smaller traps.”
Through the Working Chute
Once the bison are in the corral, the wranglers move about 50 to 75 of them at a time through a series of narrowing alleys and eventually into a “working chute,” where the check-up is conducted. Staff record data associated on unique transponders implanted in each bison’s ear; new calves are tagged during the round-up.
Because the herd has reached its target population of 2,500 animals , the preserve now sells close to as many bison as are born each spring—411 this year.
Most of the animals are purchased by meat producers, and this year Payne says the Conservancy will fetch between 70 cents and one dollar per pound per animal, with slight price differences for bulls and cows.
Return of Pure Bison—and the Prairie
By 1888, only 541 bison remained in the United States, many of which were saved by ranchers. Early on, ranchers attempted to cross-breed bison and cattle to create hearty cattle that could winter without being fed and that could better withstand the rigors of the weather.
During last year’s round-up, wranglers took hair samples from each bison as they passed through the working chute. The Conservancy sent the samples to Texas A&M University to analyze the DNA and identify any cattle genes. By next year the preserve plans to sell those bison with cattle genes.
“What we’re striving for is as genetically pure of a herd as we can reasonably attain,” Payne says, adding that Texas A&M detected cattle DNA in about 5 percent of the bison at the preserve.
Today bison are no longer in danger of extinction. The prairie that they depend on is on the rebound too—in part because of the bison. Feeding primarily on grasses, rather than the forbs (broadleaf plants) that cattle often eat, bison are helping restore the plant diversity that once existed at the Tallgrass Prairie Preserve.
“Over the last 150 years, while the cattle have grazed here, you’ve seen a shift in plant communities away from a lot of forbs to—in some cases—not many forbs,” Payne says. “When you lose plant diversity, animal diversity typically follows.”