Early Tuesday afternoon, Blue Mounds State Park manager Chris Ingebretson led a group from the Department of Natural Resources through a series of warm-up exercises.
Knowing the group of about three dozen DNR staff members and a handful of others likely would be using muscles they hadn't stressed in a while, he wanted them to stretch.
• Photo gallery: Blue Mounds bison get a checkup
The group's members would need to be loose, because soon they would be guiding a herd of bison through a metal L-shaped structure of 12 gates that to send them down a series of chutes.
In theory, the last chute collars each bison and holds the animal — which can weigh up to about 2,000 pounds — in place, where veterinarians and others begin a carefully choreographed set of moves to evaluate its health.
"They're getting blood samples, being branded, having a radio transponder inserted, and being treated for worms and pink eye," said Alex Watson, a naturalist for the DNR, who monitors the bison.
This is a busy week at the state park in southwestern Minnesota. Now that the park's 97 bison have had their annual physical, they've been pronounced fit. Next up is an auction Friday in which two dozen of the bison go up for sale in an effort by the DNR and the Minnesota Zoo to manage the state's bison herd. They are expected to bring as much as $1,500 a head.
Veterinarians aim to eventually expand the herd to 500 and preserve the bison gene pool.
The first bison into the chutes, a young male, was not amused. He kicked the metal contraption with his sharp hooves and butted the gates with his head and horns. It was a noisy but fairly typical example of how the day went; some bison made less of a ruckus, others more.
But after a few minutes, the entire exam was over, unless workers needed to brand a bison. Their goal was to keep each animal's stress low. When the exam was over, the bison galloped out to a waiting pile of prairie hay. A few passed up the peace offering and headed out onto the range.
"They're very healthy," Minneapolis Zoo veterinarian Rachel Thompson said. "We're quite impressed with the disease surveillance we've done; we've found very few concerns."
Blue Mounds gets its name from the rocky spine of Sioux quartzite that slices through southwestern Minnesota. Anyone who approaches the 100-foot mound will see blue in the distance.
Unlike nearby fields thick with corn and soybeans the Blue Mounds soil is rocky and thin, said Ingebretson, the park manager.
"Really couldn't run a plow through this land," he said. "There's rock just about everywhere in the park and Rock County where we are is named for that."
Although the land is not suitable for farming, it is good enough for six-foot-high stands of blue stem and other prairie grasses that make up most of the diet of the Blue Mounds bison herd.
The first three animals came to the park in 1961 from Nebraska. These days, the herd roams 533 fenced-in acres of the 1,830-acre park. But the ideal number would be about 70, as bison need a lot of room — from five to 15 acres each, said Watson, the DNR naturalist.
At Blue Mounds, the bison do well. The calves born each spring weigh in at about 45 pounds. By fall, they reach 400 pounds.
As the calves grow, they are hilarious to watch, said park office manager Kathy Deuschle said.
"It's like ring around the rosy and under mom, and you can see them out there just running like crazy," she said. "They don't walk, they sort of jump."
An adult bison can jump five feet in the air, which is why the Blue Mounds fences are nearly six feet tall.
Ingebretson said the bison graze as a herd, creating a black patch of heads, humps and tails as they munch their way through the day.
But he said visitors shouldn't let the animals' placid appearance fool them. The wild bison can reach a top speed of 35 miles an hour.
"The sign doesn't exist anymore," Ingebretson said, "but I've seen pictures of a sign that was here back in the '50's that said something to the effect [of], 'Can you cross the pasture in 10 seconds? Because the bull can do it in nine.'"
The wildness of the Blue Mounds bison herd became clear in 2011, when genetic testing revealed most of the animals carried no cattle genes, which is unusual.
When the bid to save bison from extinction began around 1900, it included cross breeding wild bison with beef cattle.
Geneticists now say that was a mistake as the cross-bred animals were smaller and didn't convert prairie grass to energy as efficiently as wild bison.
These days, natural resource officials aim to preserve and expand North America's wild bison. Their efforts appear to be working.
In 1885, fewer than 500 wild bison remained from the tens of millions that roamed the continent. Today, there are about 500,000. Most are in private herds destined for the dinner table, but about 7 percent are in publicly managed wild herds, like the 97 bison at Blue Mounds.
There's a much larger herd of bison across the road from Blue Mounds State Park.
They belong to John Bowron, a retired veterinarian who has been raising bison for the dinner table for years. Park personnel regard him as an important source of bison advice.
Bowron said the animals can be skittish because everyone who approaches is a threat.
"Every one of those strangers is a wolf, a predator," he said, adding that a bison who is prodded to move does not display cooperative disposition.
"They become aggressive; they challenge your authority," Bowron said. "The old saying is, 'you can drive a buffalo anywhere they want to go.'"
For all that, Bowron said bison bear their young with ease and are much less difficult to manage than the cattle he used to raise.
Bison meat appeals to those who want to eat meat with far less saturated fat than beef. Others enjoy its taste.
The meat from Bowron herd is for sale at the local Bluestem restaurant in Luverne. Chef Skyler Hoiland, who owns the restaurant, buys bison brisket from Bowron to make sliders.
"We've got braised brisket that's been in the oven for 10 hours," Hoiland said. "It's been pulled and laced with our stout beer, locally brewed in Luverne. It's got ginger pickle red onions and fresh cilantro to just brighten the flavor. That bison is going to be deep and rich and just plain wonderful."
Bison have always been part of Minnesota's ecological tapestry, DNR regional operations manager Kathy Dummer said.
"You know," she said, "big blue stem, and prairie French orchids and meadowlarks and bison."
Bison can play an important role in prairie restoration and conservation efforts. The animals have a unique grazing behavior, working the land in patches leaving grazed and ungrazed tracts of land, according to researchers at the National Resource Defense Council. They eat primarily grasses which leaves other species to flourish, aiding the diversity of prairie plants.
The animals also can create prairie habitat that helps with water retention. Bison roll in exposed soil repeatedly which compacts soil in some areas creating temporary pools in the spring.
Dummer said DNR officials plan to someday expand the state's bison herd to 500. That would help restore remnants of the prairie to their previous state and make the herd a teaching tool.
By achieving that, she said, the DNR would be "creating life-long stewards and appreciation for ecosystems and landscapes that you might only view on the National Geographic Channel or in the magazine and that still is part of the great understanding of our world."