You wouldn’t know it by looking at her, but Buttercup the miniature donkey is a fire-breathing dragon. At least that’s how Brad Wann, media relations director for the Western Pack Burro Association, described her in 2019 as she toed the usually crowded starting line at Fairplay’s annual pack burro race, the sport’s first Triple Crown event of the season. At home, she has the easygoing disposition of a therapy animal, but that day, she bounced on her hooves, held back by her owner and racing partner, Marvin Sandoval. The competitive energy was enough that her full-size, four-legged rivals gave her a wide berth.

“Marvin had his own little corner to himself,” Wann says, “and we were all like, ‘Come on! She’s 250 pounds soaking wet and taking these 900-pound donkeys to task.’ ”

It was the duo’s second race of the season—and only their second time competing together in Colorado’s official summer heritage sport, which sees both team members run anywhere between 10 and 29 miles through the mountains in homage to 19th-century gold miners. But when she and Sandoval crossed the finish line of the 26.4-mile course four hours, 58 minutes, and seven seconds later, Buttercup became the first miniature donkey to win a Triple Crown race. After winning in Leadville the following week and again in Buena Vista the week after that, she became the first mini—and only the seventh burro in the sport’s 72-year history—to win the men’s Triple Crown outright.

And it almost didn’t happen. She was, after all, discovered by accident.

While 2019 was Buttercup’s rookie season, Sandoval had competed in a single race in 2018 with a borrowed burro. Smitten with the sport, the mild-mannered Leadville local and longtime endurance athlete adopted two full-size standard donkeys (the most common breed of burro) to be his racing partners for the next season, usually late May to September. Then, figuring they’d be easier to handle, he started searching for some miniatures his kids could run with for fun.

Photo courtesy of Jennifer Mewes

After spotting a few on Craigslist in New Mexico, Sandoval drove south to check them out, but they were overweight and half wild. Discouraged, he happened to check the website again before returning home only to see that another listing had popped up for some different minis down the road. When he arrived, Buttercup walked right up and rubbed her head against him. Their connection was instant.

He adopted her (and two of her pen mates), but racing with her never crossed his mind. Then fate stepped in again. First, there was some concern that his two-year-old, full-size burros might not be fit enough to compete due to their young age, and he decided not to chance it. When his other miniature, bigger than Buttercup, started limping the day before the first race of 2019, Buttercup was his best option. They placed third, and Sandoval knew she was something special.

Local media outlets like Summit Daily and the Leadville Herald, plus some national ultrarunning publications, seized on Buttercup as the ultimate underdog: At just 32 inches tall (measured from the ground to the base of the neck), she was so undersized that she could almost walk under the bellies of her competitors. Then in 2020, Buttercup did something no one expected. She won the Triple Crown again. In fact, at press time, she and Sandoval had never finished off the podium in their 13 races together.

“I think she knows it’s a competition because when we’re headed out on a training run or walking in a parade, she is so mellow,” Sandoval says. “But at the starting line, she’s excited and there’s something different about her.”

Buttercup racing against standard donkeys in Buena Vista in 2020. Photo courtesy of Amy Wanke

No longer the dark horse, Buttercup is now the burro to beat. During 2020’s final Triple Crown race, she and Sandoval were in the lead with another team, the donkey equivalent of a Tour de France breakaway, and the peloton was gaining on them. “Come on,” Sandoval remembers saying to the human half of the other team. “Let’s push together. At least one of us will win.” The other runner turned to him: “I’d rather us both lose than see you win.”

Buttercup and Sandoval won anyway, and when the duo lines up again in Fairplay on July 25 for the first Triple Crown race of 2021, there will be only one question on everyone’s mind: Can she do it again?

This article was originally published in 5280 July 2021.
Nicholas Hunt
Nicholas Hunt
Nicholas writes and edits the Compass, Adventure, and Culture sections of 5280 and writes for