The herd of bison stood munching on native grasses, their enormous heads bowed. Suddenly, realizing their leader had moved about 100 yards away, the six bison broke into a run, rushing to join her.

The bison's movement gave the handful of people watching a taste of how the prairie may have looked — and functioned — over a century ago, when tens of millions of bison lumbered across Minnesota and other parts of North America..

A herd of American plains bison now inhabits Spring Lake Park Reserve in Hastings, the culmination of years of work by county officials to bring the animals to about 150 acres of restored prairie there.

"This is a wonderful experiment for us," said Tom Lewanski, Dakota County's natural resources manager, adding that the county will survey the bison's impact on birds, mammals, bees and plant life.

"Bringing it from 'It was just an idea' to actually having the bison ... out on the prairie is very rewarding," he said.

The seven animals — all from the Minnesota Bison Conservation Herd — came from Blue Mounds and Minneopa state parks in early October. The herd may one day number 15 animals, but for now the all-female family is simply becoming accustomed to their new Dakota County digs.

"They need to get to know each other," Lewanski said. "They're in a new home."

The herd is comprised of a yearling cow, two 2-year-old cows and two cow-calf pairs. One or two calves are expected to be born in the spring, Lewanski said, and a bull will join the herd in fall 2024.

County staff didn't want to "add in the whole breeding thing," he said, until both the staff and the bison were accustomed to the animals' presence in the park.

Dakota County once consisted of more than 300,000 acres of prairie and oak savanna, upon which thousands of bison roamed. Less than one-tenth of 1% of that area remains.

Bison — known as a keystone species, or one that other plants and animals in an ecosystem depend on — are an important piece of the county's prairie restoration efforts at Spring Lake Park. They help maintain the prairie by grazing, mowing down grasses and leaving more space and sunlight for wildflowers and other plants.

The bison also impact the prairie through wallowing, or rolling around, which exposes mineral soil that helps more seeds grow. And the wallowing creates depressions in the soil where water settles, forming watering holes that become breeding habitat for frogs, toads and salamanders, Lewanski said.

Over time the bison herd will be moved to eight different fenced paddocks across the park, each about 20 acres. They will be less visible to visitors in fall and winter but brought closer to the main trail in the spring, said Carleigh Dueck, Dakota County's natural resources bison technician.

"It's great to see them bounding and happy on the prairie we've been restoring," Dueck said.

The project was funded with $851,000 in state bonding money, and the cost of the fenced paddocks was covered by a $560,000 grant from the Minnesota Environmental and Natural Resources Trust Fund.

About 300,000 bison inhabit North America today. There are at least three other bison herds in the metro area: the Cedar Creek Ecosystem Science Reserve in East Bethel, the Belwin Conservancy in Afton and the Minnesota Zoo in Apple Valley.

Dakota County is the only Minnesota county to have its own herd.