What Bison Teach Us: A Decade of Growth and Conservation in the Chicago Area

Three centuries ago, 40 to 60 million bison roamed North America, including across the grasslands of Illinois. They grazed on native grasses, wallowed in the soil and gave birth in late spring. Though humans will never be able to experience that scene again, they can see bison in their natural habitat at three regional locations: Nachusa Grasslands, in Franklin Grove; Midewin National Tallgrass Prairie, in Wilmington; and Kankakee Sands, in Morocco, Indiana.

Bison were introduced in small numbers at these sites between 2014 and 2016. Today, the combined population at the three locations is about 300.

Since the reintroduction, scientists have been studying how bison interact with the landscape and have gained valuable insight to guide future restoration endeavors.

“We have also learned just how important these buffalo are from a cultural perspective,” says Dr. Elizabeth Bach, research scientist at Nachusa Grasslands, which is managed by The Nature Conservancy (TNC). Bach works with scientists, land managers and volunteer stewards to study tallgrass prairie restoration ecology, including how the bison interact with the landscape.  

“We understand that these animals, not only from an ecological standpoint, are integral to the tallgrass prairie, but also that they were a pivotal part of the Indigenous nations and communities who lived and worked on this land,” Bach says.

Native Americans relied on bison for food and clothing, as well as spiritual needs. Hunted to near extinction by European settlers, only about 1,000 bison remained by the turn of the 19th century.

In 1904, the American Bison Society was founded to save the species from extinction. The population has since grown to about 500,000, with 30,000 living on public lands such as parks and preserves, and the rest on private land and commercial operations.

The introduction of bison into conservation lands is an experiment in restoring tallgrass prairie. “Buffalo are part of that ecosystem,” says Bach. “We want people to appreciate and fall in love with that ecosystem.”

“Tallgrass prairies co-evolved in Illinois as ecosystems with grazing from animals like bison and also through fires set by Indigenous peoples who were using it to manage the landscape,” Bach explains. “It’s a system that is tolerant and dependent on regular disturbances from grazing and fire. Here at Nachusa, we’ve had the opportunity to do prairie restoration on a large scale of a few thousand acres.”

Bach adds, “All of the prairie restoration efforts across the state are important, no matter the size, but here we have the opportunity to work on ecosystem factors in bigger ways.”

In October 2014, 30 bison—descended from a wild herd in South Dakota—were introduced to Nachusa Grasslands from preserves owned by TNC. In 2015, the U.S. Forest Service introduced 23 bison cows and four bulls to Midewin National Tallgrass Prairie. TNC continued the effort at Kankakee Sands in 2016 when 23 bison were introduced there. TNC manages 11 herds of bison in North and South Dakota, Nebraska, Iowa, Illinois, Colorado, Kansas, Missouri and Oklahoma.

These bison live wild lives: They breed, give birth, feed on native grasses and sedges, and care for themselves without human intervention. They endure weather extremes, parasites and predators just as their ancestors did centuries ago.

Each fall, the bison are rounded up for counting. As herds reach capacity, animals are relocated to other preserves or ranches. The Nature Conservancy transfers bison from Nachusa Grasslands and Kankakee Sands to the InterTribal Buffalo Council.

“I feel in awe and humbled to be out on the landscape with the bison,” Bach says. “We want them to behave as they have for millennia. We want them to interact with the ecosystem. We intentionally try to keep human action to a minimum. We keep a safe distance, and I remind myself we’re only a small part of the buffalo, bees, birds, butterflies and plants in the prairie. We are all connected.”

Studies are being done to learn more about buffalo interaction with other species and ways they affect the tallgrass prairie.

A Nachusa study published in November 2024 found that during the first five years, there was no statistically significant difference in plant diversity between grazed and ungrazed lands. “But that was the first study, and we’re in it for the long term,” says Bach, noting that another five, 10 or 20 years could tell a different story.

Another study at Nachusa and Kankakee Sands shows that grazing bison interact with prescribed fire to structure habitat for grassland birds, including Henslow’s sparrow, which was once endangered in Illinois. Bison grazing has also been associated with increased populations of ground and dung beetles and changes in small mammal foraging behavior.

“The big take home message is that we want to create a patchy habitat where these different animals and plants can thrive,” Bach says. “That’s promoting diversity. That’s how tallgrass prairie has functioned for millennia. Having a mosaic of grazed lands and burned lands is what makes the tallgrass prairie work.”

Another good ecologic deed performed by bison is their habit of wallowing—rolling in dust to protect themselves from insects and interact with the herd. “When bison wallow, they create shallow depressions on the prairie, which fill with rainwater and can provide habitat for amphibians, reptiles, insects and early successional plants,” according to TNC’s Kankakee Sands website.

Bison preferentially graze on grasses and sedges, giving an advantage to flowering plants and the insects and animals that those plants support. In addition, bison dung adds nutrients to the landscape, and their fur serves as nesting material for grassland birds.

“The bison really has brought a lot of people to Nachusa,” Bach says. “It has brought people to the landscape and to feel that connection with the land.”

Sheryl DeVore has written six books on science, health and nature, as well as nature, health and environment stories for national and regional publications. Read more at SherylDeVore.WordPress.com.

Bison or Buffalo?

The genus and species for the American bison is Bison bison. The term “buffalo” has become a common name for bison indigenous to North America. The word “buffalo” carries important cultural significance for many Indigenous nations and communities.

 

Where to View Bison Near Chicago

While keeping bison as wild as possible, officials encourage visitors to see the buffalo and experience the prairie. Visitors can view bison herds with their young, watch them wallow and listen to them interact with interesting vocalizations. For safety reasons, visitors are not allowed in bison roaming areas, and there’s no guarantee the animals will be visible. Here’s how to view them.

At Nachusa Grasslands, in Franklin Grove, visitors can see bison from Lowden Road, Stone Barn Road and Naylor Road as well as the visitor center parking area from dawn to dusk. A good chance to see them is on September 20 at Friends of Nachusa Grasslands’ Autumn on the Prairie, which includes guided hikes and a hay wagon ride (NachusaGrasslands.org).

At Midewin National Tallgrass Prairie, in Wilmington, bison roam a 1,200-acre fenced pasture. Access the viewing area year-round from the Iron Bridge Trailhead, which is 2.9 miles north of the welcome center (fs.usda.gov/r09/midewin/animals-plants/bison-project-homepage).

Kankakee Sands Bison Viewing Area, located off U.S. Highway 41, is open from 7 a.m. to dusk. A short, gravel walking path leads visitors to a sand-topped dune to view bison and the landscape (Nature.org/en-us/get-involved/how-to-help/places-we-protect/kankakee-sands).