A coalition of ranchers, environmentalists and Osage Nation landowners are working together to save the grasslands.

The late October morning is so bitterly cold that the vaccine a hardy Oklahoman cowboy is trying to administer to an impatient bison has frozen.

The rancher, Harvey Payne, tries to defrost the liquid against a small heater pumping out hot air in the office that faces the corral, but it’s not working.

“We’ll have to head back in for a couple of hours and wait for the sun to warm up,” Payne says as he squints at the sun rising above the tallgrass prairie. “Can’t vaccinate bison with frozen antibiotics.”

The group that’s gathered at the Joseph H. Williams Tallgrass Prairie Preserve trudges back to headquarters to wait until the temperature rises.

Oklahoma’s 39,650-acre preserve is the world’s biggest protected remnant of a massive grassland ecosystem that once stretched across 14 states, covering 170 million acres. But the grassland has been decimated, and only about 4 percent of the ecosystem remains, most of which is contained in the preserve in Osage County, home to the Native American Osage Nation.