When it comes to bison, a Twin Cities park is in the middle of a baby boom.

Last month, Spring Lake Park Reserve in Minnesota was surprised by the birth of not one, but four new calves.

Natural Resources Manager Tom Lewanski has had a hand in restoring about 150 acres of prairie between Rosemount and Hastings and the land has responded, but one thing that’s been missing is the grazers.

“The native grazer in North America was the bison. At one time, there were between 40 and 60 million bison that roamed across the prairies of North America,” he said.

180 years ago, they were killed or driven off by European settlers. But last fall, eight females were reintroduced to this park, coming from Blue Mounds and Minneopa State Parks, where similar efforts are taking place.

Little did Lewanski know, these bison arrived with a bonus.

“And lo and behold, one of the 2-year-old cows gave birth. And 24 hours later, another one of the 2-year-olds gave birth,” said Lewanski.

Two more cows also had calves last month, for a grand total of four babies. And each one will play an important role in prairie restoration.

“Bison can weigh up to a ton and their impact is huge. By being here they are helping wildflowers, insects and much more,” said Lewanski.

About 95% of their diet is native grasses. By eating them, native flowers can flourish.

“It’s a cascade effect if you will. The more flowers you have, the more insects you have. The more insects, the more birds and mammals and things like that. It really helps to develop the whole community,” said Lewanski.

By doing so, they also hope to educate visitors on what the bison of yesteryear and today mean to the Dakota people.

“Providing the opportunity to help tell that story is another exciting component of this project,” Lewanski said.