SIOUX FALLS, S.D. (KELO) — The thousands of bison that roam state and federal land in the Upper Midwest are a far cry from the millions that once inhabited the plains 200 years ago.

But, today’s bison are linked to those ancestors in an organized effort to preserve the animals. The preservation for today’s herds started in zoos or in private herds in the U.S.

Zoos such as the Bronx Zoo preserved bison in the late 1880s and early 1900s.

Ranchers were also key in the preservation of bison.

Chris Ingebretsen, the park manager at Blue Mounds State Park near Luverne, Minnesota, said ranchers were mostly interested in bison as a source of meat.

“They would breed them with cattle,” Ingebretsen said. “They were looking for a big piece of steak and animal that would survive the winter (on the plains).”

Ranches were the source of the herds at Custer State Park in South Dakota and Fort Niobrara National Wildlife Refuge in Nebraska, and indirectly, they were the source of the herd at Blue Mounds since that herd started from Fort Niobrara.

Bison were introduced to the Fort Niobrara National Wildlife Refuge in 1913. The animals came from a private herd in Nebraska, said Matt Sprenger, the refuge manager for U.S. Fish and Wildlife at Fort Niobrara.

A 1975 history of the herd said the bison were turned loose on the refuge “without loss or accident” on Jan. 21, 1913.

The original 36 bison at Custer State Park came from Scotty Philip’s herd near Fort Pierre in 1914, the South Dakota Game Fish and Parks (GFP) said.

The first animals at Wind Cave National Park in South Dakota came from the Bronx Zoo in 1913, said Greg Schroeder, a science and resource manager for the National Park Service at Wind Cave. That was in 1913. In 1916, several animals came from Yellowstone National Park, Schroeder said.

The herd at Blue Mounds started in 1961 with “two bulls and a cow from the Fort Niobrara National Refuge in Nebraska,” Ingebretsen said. “The herd grew and over the years another 540 acres of prairie was added.”

Why manage and preserve bison?

State and federal officials have acknowledged the strong indigenous ties to bison as well as the ecological benefits for preserving bison herds.

“Bison have played a key role in the management of grasslands at the refuge.  Research suggests that grasslands managed with bison show a greater level of plant diversity than areas managed with cattle or without grazing,” Sprenger said.

Schroeder said vegetation that may have existed once in a grassland has returned after bison were introduced.

Bison tend to graze unevenly which leaves areas of short and tall vegetation, Sprenger said.

A wider variety of birds benefit from a diverse vegetation.

On grassland in the Pine Ridge Reservation area, bison dug up springs of water, he said. Cattle would not have dug up such springs on the grass, Schroeder said.

The bison “is a defining symbol of the American west,” said Tom Farrell of the NPS. Farrell said a bison can inspire someone to stop “five and 10 minutes” and watch and listen. During certain times of the year “It’s amazing how much noise they can make,” he said.

“It’s a pretty exciting time in the world of bison,” Schroeder said. “There is a lot of momentum on expanding bison on the landscape.”

The herds started by private herds or zoos now help establish other herds in the U.S. including on tribal lands.

In the past 25 years, the preservation of bison has been supported by each presidential administration, Schroeder said.

Wind Cave has helped establish bison herds on the Rosebud Reservation and in Arizona. Other entities have also participated.

Frozen embryos from the Yellowstone herd

Ingebretson and Schroeder said it’s difficult to find a herd without some cattle integration since cattle were bred with bison as the bison herds were destroyed.

“In 2012, we began partnering with the Minnesota Zoo on a bison conservation herd,” Ingebretsen said. The goal is to have a bison herd as free in genetics from cattle integration as possible.

The state does genetic sampling on the herds. “We definitely see Fort Niobrara genetics that are still prevalent,” Ingebretsen said.

Blue Mounds has helped start herds at Minneopa State Park near Mankato, Minnesota, and other preservation areas in the state.

Yellowstone National Park bison are generally considered the most genetically pure but access to that genetic line in a transfer of any animals is not allowed.

Yellowstone bison carry brucellosis, a disease that can cause pregnant bison to abort their fetuses. That prevents the integration of Yellowstone bison with other herds.

But the frozen embryos allow for integration, Ingebretsen said.

Within the past several years, frozen embryos from a Colorado State University project have been used to help build a bison herd, Ingebretsen said.

The herd at Wind Cave is a closed herd, Schroeder said. That means breeding is contained to the existing herd.

“We’re maintaining most of the national park bison herds as closed herds,” Schroeder said.

How big do the herds get?

Wind Cave will have a herd of about 500 to 550 head by the end of summer, Schroeder said.

“We manage at the low end, what the range can withstand, ” Schroeder said. That practice means the NPS doesn’t have to be as reactionary if there are dry conditions or other factors that could force cutting the herd size, for example.

The bison roam freely in the park and there is no winter feeding or similar help from the NPS.

Wind Cave still needs to manage the numbers with a roundup.

Since it’s not a domestic herd, Wind Cave does a random reduction that is not based on size or sex. That keeps the herd more natural, Schroeder said.

When it does a more formal reduction, it will reduce about 80% of the yearling and two-year-old animals, Schroeder said.

Any animals removed from the herd do not go to private land or owners, Schroeder said.

At Custer State Park the herd’s typical annual numbers have grown to 960 head over winter with 400-500 calves each season, the SD GFP said. The spring herd can total 1,360 to 1,460 head — bringing the numbers up to 1,360-1,460 head.

Custer does an annual round-up each year for about 400 to 500 surplus head. Surplus head are sold at auction. Bison have gone to nearly all 50 states and most Canadian provinces in the past 58 years of the auction, SD GFP said.

Blue Mounds has a winter herd of about 55 with 25 to 35 calves born each spring.

While it works with other organizations to establish and expand bison herds, there are times when some of the herd at Blue Mounds is sold at auction. The buyers tend to be private owners, Ingebretsen said.

The Fort Niobrara Wildlife Refuge has a herd about 350 head on about 16,000 acres, Sprenger said.

Fort Niobrara also does an annual roundup.

“During the roundup, we remove an equal number of males and females so the sex ratio of the bison we keep is one-to-one,” Sprenger said.

Bulls tend to have a higher mortality rate so the number of females will get higher than males, Sprenger said.

Can you see the bison herds?

The bison can occupy thousands of acres, depending on the location but all four officials said the public often has a chance to view bison.

“Bison are the biggest draw to Blue Mounds,” Ingebretsen said.

The park offers regular bison tours. The schedule can change depending on the season. The public can also walk a prairie trail near the bison.

Fort Niobrara has two hiking trails and wildlife can be observed by driving.

The bison co-exist with a variety of other wildlife including elk, deer, mountain lions, turkeys, coyotes, badgers and a variety of grassland birds, Sprenger said. 

Visitors to Wind Cave National Park can also see bison. The park also offers a story map about the bison on its website.

“I think it’s amazing to see a small glimpse of what it was like 1,000 and 500 years ago,” Schroeder said of watching bison the park.

One of Custer State Park’s big draws is the bison herd.