MANKATO — The first bison calf of the year was born Wednesday at Minneopa State Park, with more on the way.
On Thursday afternoon the baby was romping around the prairie. Mom stayed close behind, often charging to chase off yearling bison that were too curious as they got close to the newborn.
Eight years ago the Department of Natural Resources started the herd at Minneopa, bringing in genetically pure bison from Blue Mound State Park and elsewhere.
From the end of April to mid-May a major stream of visitors comes to the park as the calves are born. Nearly every bison in the U.S. is born in that short window because of something called birth synchrony.
It is an evolutionary adaptation that helps the cows and the calves. Being born in early spring gives the young time to grow strong before the next winter sets in and the cows, after going through winter and the stress of birthing, will have green grass available to rebuild their strength and optimize milk production.
Still, some are born late. One calf was born last October and is doing well.
The Minneopa bison and some of the other herds being built up in the state are relatively unique because they have high-quality genetics descending from the type of bison Lewis and Clark gazed upon in the 1830s. After the millions of bison that once covered the West were slaughtered almost to extinction, many of the remaining bison were cross bred with cattle and lack a pure genetic line.
Minneopa is part of the Minnesota Bison Conservation Herd, which is managed by the DNR and the Minnesota Zoo to preserve genetically diverse bison.