MEDORA, N.D. — A group of six riders had just finished packing and started on a trail ride through the Badlands at Theodore Roosevelt National Park when a wild horse came scurrying down a butte toward them.

“All of a sudden I heard a whinny come from up on the bluff,” Kelly Ringer said. She was one of the riders visiting the park from Park Rapids, Minnesota. “He came barreling down.”

The horse’s dramatic arrival came with a spirited exchange of whinnying and neighing as the wild horse, a 5-year-old stallion named Alluvium, and the horses in the riding group chatted.

At first, Ringer, who was riding a young horse who had never before been exposed to a wild horse and was unfamiliar with the terrain, was concerned. But her worries quickly faded.

“It was magical,” Ringer said. “He was fine. He wasn’t aggressive.”

It soon became apparent that Alluvium had a particular interest in a “little mare” named Gypsy in the riding group, she said, which was departing from the Roundup Group Horse Camp 12 miles from Medora in the park’s south unit, where 185 to 200 wild horses roam.

“He decided to hang around” and followed the group as it left for the trail ride on Thursday, May 16, Ringer said. Alluvium circled the riders and after about five minutes, Ringer’s horse, Boone, bucked, and she fell. She was not hurt.

“That’s just what horses do,” she said. “It wasn’t a big deal.”

Alluvium followed the riders for a time but stopped after a while, seeming to keep to a certain area while avoiding others.

“I think that was probably his territory,” and he appeared to regard other areas as off-limits, possibly because they were the turf of other wild stallions in the park, Ringer said.

The wild horses are organized into social groups called bands, each led by a stallion.

Later on during the ride, when Alluvium was no longer tailing the group, Ringer’s horse again bucked, possibly spooked by some brush.

“It’s horses,” Ringer said. “They have a mind of their own. It’s a risk that you take.”

Horse advocates have said Alluvium, a bachelor stallion, was acting naturally by trying to recruit mares to form his own band.

Ringer and her fellow riders had another drop-in visitor at Roundup Group Horse Camp — a bison that came up close to the corral and charged, spooking Boone, who was inside the corral.

“He took a couple of charges at the corral with my horse in it,” she said. “That was a little unsettling.”

But the group of riders came to the park knowing that it is home to wildlife, including horses and bison, Ringer said.

“These are just risks that you take,” she said. “What would that park be without the bison and the wild horses? The park would not be what it is without the wildlife, and that includes the wild horses.”

During their stay, a park ranger paid a visit to the group of riders at Roundup camp, and they told him about their encounter with Alluvium.

“We didn’t necessarily report it,” Ringer said. “We didn’t contact the park, but a ranger came in one day and the horse (Alluvium) was there and asked if he was a nuisance.”

Ringer mentioned that she had been bucked off. The ranger asked if they wanted Alluvium removed and was told no. The ranger left soon after, and Ringer thought no more of it — until she learned the park considers Alluvium a “nuisance animal” that poses a danger to the public and will remove him from the park.

“That’s why I feel so bad,” she said. “We told the ranger, ‘No, leave him.’”

She added: “This is a young bachelor stallion. He’s just doing what is natural. Horses are herd animals.”

Another rider in the group, Kaylee Bickey, also of Park Rapids, said Alluvium was not acting aggressively around Gypsy and the other horses.

“He wasn’t really trying to cut her out or anything,” she said. “When we said, ‘Git,’ he got, he went away. He just wanted other horses to be with.”

After their ride, when Gypsy was returned to the corral, Alluvium stayed close by.

Bickey’s recollection of the discussion with the park ranger about Alluvium matched Ringer’s.

“We told the ranger about him, but we never complained. We went to see wild horses. It was probably a top-five experience of my life.”

The riders brought young horses that hadn’t experienced situations like those in the park and reacted more than seasoned horses would have, Bickey said.

“It wasn’t any fault of Alluvium,” she said. “It was our fault for not exposing them to things before just taking them out. Once they had been around him for a little bit, they were fine.”

Ringer, who has ridden horses for 30 years, recalled encounters with dogs, deer and even inanimate objects that spooked horses. “If I would go and eliminate something every time it spooked my horse — that’s just insane,” she said.

Park officials have not given interviews about Alluvium but issued statements.

Park Superintendent Angie Richman said Alluvium was “harassing visitors and visitor’s horses at the horse camp campground. Park staff relocated it once and it found its way back to the camp the next day. This is a nuisance animal that can potentially harm visitors or their animals.”

Park officials have been holding Alluvium in a pen for several weeks “until it can be sold or transferred to a tribal partner or other government agency,” Richman said earlier.

Chris Kman, president of Chasing Horses Wild Horse Advocates, asked park officials to allow Alluvium to stay in the park. He was in his home and acting naturally in the encounter with visiting horses, she said, noting bison are dangerous but remain in the park, apparently even after goring visitors.

By describing the horses as livestock instead of wildlife, a term the park formerly used, park officials are doing a disservice to visitors by making the horses seem tame, Kman wrote in an email to Richman.

In an interview, Kman said it appears Richman is determined to reduce the size of the herd, and Alluvium’s encounter with the mare provided an excuse to get rid of a horse. She said a horse trailer has been parked near the pen where Alluvium is being held, apparently in preparation for transporting him.

Park officials did not directly respond to the points raised by Kman or the account given by Ringer and Bickey that found no fault with Alluvium’s behavior.

“I would adopt him if I could,” Bickey said. “For a wild horse, he was pretty well-behaved.”

Park officials haven’t yet made arrangements for an auction sale of Alluvium.

“We currently do not have any additional details concerning an auction,” Maureen McGee-Ballinger, deputy park superintendent, said in an email. “When/if there is an auction, the details will be announced.”