An open-air tour vehicle jostled across the prairie at Blue Mounds State Park, as 12 riders grabbed onto hats and rails. With more than 500 acres set aside for a resident bison herd, it can take some guesswork to figure out where North America’s largest land animals have wandered for the day.
“Bison can consume 26 pounds of prairie grass a day,” lead naturalist Tiffany Mueller told the group. That’s aided by a four-chambered stomach and nine to 10 hours of daily grazing.
She stopped a safe distance from a bull brought in from Yellowstone National Park. An estimated 30 million bison roamed the Great Plains until herds were slaughtered in the 1800s. Mueller said only 50-some bison survived back then, and all but 1% of native tallgrass prairie was carved up.
An ongoing effort seeks to bring back the bison population and keep them genetically diverse and healthy, which is why bulls might be transferred from Yellowstone to help with Minnesota’s Bison Conservation Herd, a partnership between the Minnesota Zoo and the Department of Natural Resources.
Bison have roamed the state park, 3.5 hours southwest of the Twin Cities, since 1961. In early summer, cinnamon-colored calves sprint rambunctiously around the dark-brown females before pausing to nurse or nap in the lush prairie grasses.
“Our herd is a little over 100 animals,” Mueller said, and the daily tours at Blue Mounds offer one of the best chances in Minnesota to see and learn about the bison, which play an essential role in restoring prairie ecosystems.
They aerate and fertilize the soil, they seem to know to graze around the wildflowers that pollinators need, and they roll onto their backs in the dirt to help shed winter coats and get relief from biting insects, leaving behind wallows that fill with rainwater used by amphibians, birds, gophers and prairie dogs.
“They really are quite special,” she said of the herd. “I never get tired of seeing them.”