“It was a wonderful surprise,” said Tom Lewanski, when two baby bison were born back-to-back last weekend at Dakota County’s Spring Lake Park Reserve.

When eight bison were relocated to the park last fall, Lewanski, who works as the park’s natural resource manager, said they were keeping an eye on the lead bison and had suspicions she was pregnant.Much to their surprise, a 2-year-old bison gave birth to a new calf on April 28 and, 24 hours later, the other 2-year-old bison gave birth as well.

“It was a total surprise,” Lewanski said.

Located northwest of Hastings, the park is along the Mississippi River and includes around 160 acres of prairie landscape.

During the winter months, Lewanski said the bison were mostly out of public view to give the herd time to bond and create its own social structure.

“We intentionally secluded them so they could form their own herd … We wanted them to get to know each other and their new home,” he said, adding that the adult bison came from three different herds around the state.

Last Thursday, for the first time, the herd was moved to a different paddock, Lewanski said. The relocation went smoothly, he said, and the herd, including its new calves, is now more visible to the public.

The newborns are not difficult to spot, Lewanski said, as they weigh around 50 pounds and have lighter coats compared with adult female bison, which can weigh up to 1,000 pounds.

Returning to the prairie

Bison are being reintroduced to the prairie to boost plant diversity through their grazing habits, Lewanski said. When bison graze, they allow wildflowers to thrive by eating the tall grasses and they also help to work native seeds into the soil, according to the county parks.

Before European settlement, bison were an important historical and cultural component to the Indigenous communities that cared for the land that is now known as Dakota County. For this project, the Tribal Historical Preservation Office of the Upper Sioux Community was consulted, according to park documents.

The project to bring bison back to the prairie has been in the works for the past four years, Lewanski said. A $560,000 grant from the Minnesota Environment and Natural Resources Trust Fund helped to make the program possible.

The funding was used on infrastructure needed in the park to support the bison, Lewanski said, including fencing, water troughs and gates for the mammals.

As for the new calves, Lewanski said “They are doing really well.” Each calf’s mother will take care of her own, but the herd will step up to protect the newborns as needed, he said.

The program is looking to add its first male to the herd near the fall of 2024, Lewanski said, with the intention to breed offspring. The next time there will be calves in the park will not likely be until the spring of 2026.