Illinois: Land of Lincoln, the Windy City, and Now, Bison
Where do the buffalo roam? These days, you can find them about 100 miles outside Chicago as bison return to Illinois for the first time in nearly 200 years in an effort to restore a long-lost ecosystem.
Unlike with the reintroduction of gray wolves in the American West, people are welcoming the return of the bison; it’s the first time wild members of the species have come east of the Mississippi River since the 1830s.
“We’ve got people lining the fences here taking pictures,” said Cody Considine, a restoration ecologist who’s been working at the Nature Conservancy’s Nachusa Grasslands preserve in Franklin Grove, Illinois.
Illinois may fashion itself the Prairie State, but only 1 percent of the long, tall grasslands that once dominated the region survive. At Nachusa, the Nature Conservancy has spent the past 20 years removing invasive species and restoring natural plants to the 3,200-acre reserve. But the prairie had been missing a key component—bison.
The Nachusa bison came from the Wind Cave herd in North Dakota, one of only four free-roaming and genetically pure herds left in North America.
In October, the first 20 bison made the eight-hour trek from the Nature Conservancy’s Broken Kettle Grasslands preserve in Sioux City, Iowa, to Nachusa Grasslands. More bison were introduced in November and December, and the herd numbers 30 today.
With the wildest bison and the most natural prairie setting in the state, the site is attracting researchers and scientists waiting to see just how much of an impact bison can have on an endangered habitat such as Illinois’ prairies.
“They’re a keystone species in the prairies, and all of the things they do in the environment can add up to big impacts on the surrounding animals and habitat,” Considine said.
So what makes bison so critical to grasslands?
First off, their appetite. Bison graze young grasses down to the nubs but skip over wildflowers and other native plants. That gives a variety of plant species space to grow and gain a stronger foothold in the prairie.
Second, their weight. Bison hooves leave imprints in the soil, which helps space out plants. When they lie down, their 2,000-pound bodies create depressions where small pools can form in the rainy season—the perfect habitat for amphibians and reptiles, such as the threatened ornate box turtle.
Last, their poop. Bison pies are elixirs of nutrients for the prairie, spreading seeds, fertilizing the soil, and attracting insects—such as the dung beetle—to the region. Luckily for the box turtle, more dung beetles in the area means more meals for them as well.
“But it’s even more than that,” Considine said. “It’s the little things too—when bison shed their winter coats, small animals have been recorded using their fur to build nests. That could increase their population, which could attract larger predators to the area.”
Researchers at Southern Illinois University will be comparing the Nachusa herd with Kansas’ Konza Prairie group, where long-term research on bison impacts on tall-grass prairies have been ongoing since the 1980s.
“What we've learned there will help guide us toward restoration of Illinois prairie ecosystems,” James Garvey, vice chancellor for research at the university, said in a statement. “Our hope is that a similar system, long-term restoration and research site may be maintained in Illinois, providing new insight into the similarities and differences between Kansas and Illinois prairies, their bison and other heritage organisms.”
There were 30 million of the behemoths across North America in the 1500s. By the late 1800s, commercial hunting and intentional slaughter had whittled that number down to about 1,000. Today, after nearly a century of restoration, around 500,000 bison reside in North America—but only about 30,000 are truly wild and only 5,000 of those are unfenced, mostly in Yellowstone National Park.
The Nachusa herd is part of the fenced-in population, roaming 500 acres of land in the preserve. While the Nature Conservancy has plans to expand the grazing area to around 1,500 acres and grow the herd to 120 bison, the animals will never be fully free.
“We’ll never have free-roaming bison in this state like there was before—we’re not trying to hang our hat on that,” Considine said. “What this project is about is restoration. It’s a model of how we can hopefully restore the prairies that have disappeared by 99.9 percent in this state. The future is restoration.”