Bison’s Return

There used to be enormous herds of bison that roamed North America…and by enormous, it means tens of millions. However, now, it is rare to see the passing herd…but what if they one day came back?

A recent study suggested that bison could restore the environment, and people believe they still can. “If we value a system (to support the bison), we need to allow it to operate as close to naturally as possible,” Bill Hamilton, an ecologist at Washington and Lee University and an author of the study, had said.

Despite increasing interest in restoring bison across North America, most projects focus on small, managed herds. But still, Hamilton was faced with doubt regarding the benefits the bison would bring; to address this situation, he, along with John T. Perry Jr., Professor in Research Science at Washington and Lee University, and Chris Geremia, a National Park Service scientist at Yellowstone, studied the bison’s grazing behavior during the spring and summer months.

From 2015 to 2022, Dr. Hamilton and his team conducted extensive research, including installing a movable enclosure at one of the dry-habitat sites in the summer to quantify the amount of grass consumed by bison and other herbivores. Monthly soil samples were also collected to compare how specific sites thrived with or without bison. According to their research, Yellowstone could sustain up to 5,000 bison today. Each year, the herd travels nearly 1,000 miles, mainly feeding on new plant growth after the snow and ice thaw, though this would seem to be an overuse of vegetation. Research shows that plants could become significantly richer in nutrients…which is up to 150% more nutritious. The scientists discovered that this process could increase the number of microbes, leading to more nitrogen available for animals and plants to use.

“What we’re witnessing is that as bison move across the landscape, they amplify the nutritional quality and capacity of Yellowstone,” Hamilton said. “Their grazing likely has important consequences for other herbivores and for the food web as a whole, similar to the changes that occurred in the Serengeti when the wildebeest population recovered.”

Yellowstone had always served as a location for ecological restoration, and this new research mainly served the purpose of highlighting the benefits bison could bring to reshape the land. “The connection between Indigenous people and buffalo has never been broken,” Mr. Heinert said. “But the restoration is extremely important, so that our younger generations know what having buffalo on the landscape means for the environment.”