The Minnesota Zoo is announcing the arrival of two newborn bison, and they carry the important distinction of being genetically pure.

They're the first bison born at the zoo in Apple Valley in 20 years.

Bison, the largest land animals in North America, have been on exhibit at the zoo since 1980. The zoo has been working this past year with the Minnesota Department of Natural Resources to manage a herd at state parks and at the zoo.

A herd of nearly 100 bison roam at Blue Mounds State Park in southwestern Minnesota, a project that started in 1961 with three animals from Nebraska. Testing has confirmed that the herd at Blue Mounds is nearly genetically identical to bison that existed before European settlement. Blue Mounds welcomed its first calf in late April.

The zoo now has 10 bison on its Northern Trail. The two new calves, both female, are destined to be released into state parks in the fall of 2014.

The two newborns have different mothers and the same father. They are all from the Blue Mounds park.

The mothers were brought to the zoo in time to give birth, one on April 27 and the other on May 8.

"The birth of two calves in our newly assembled bison herd is a great first step toward achieving the goal we share with our partners at the DNR," said Minnesota Zoo Director Lee Ehmke, "the restoration of wild bison to parts of their historic range on the state's prairie landscape."

During recovery of bison from near extinction in the early 1900s, cattle interbred with bison in many locations. Recent scientific advances estimate that less than 1 percent of the world's remaining American bison are free of cattle hybridization, posing a serious threat to the long-term conservation of pure wild bison across the nation.

This new effort helps protect the genetic diversity of this native Minnesota species and educate Minnesotans about the bison's conservation story and the important roles bison play in the prairie ecosystem.

Before Europeans settled across North America, the bison population was estimated to be from 30 million to 60 million. Hunting brought the species to near extinction in the early 1900s.

Currently, there are about 19,000 plains bison in 54 herds managed by governments and environmental organizations. Bison are also raised as livestock and are considered a healthy alternative to other red meats.

Male bison can weigh more than 2,000 pounds, while females typically top out about 1,100 pounds. At birth, they can weigh from 40 to 50 pounds.

Paul Walsh • 612-673-4482