Feral horse

Ranch horses turned loose on the open range and never gathered back. Their descendants live in Theodore Roosevelt's South Unit as feral livestock.

We saw it Our family spotted this one at Theodore Roosevelt National Park in September 2026.

  • A horse on the badlands rim in Theodore Roosevelt National Park.Amaury Laporte
  • Horses at the Little Missouri River in Theodore Roosevelt National Park. Bands run 5 to 15 animals.Farragutful
  • A horse crossing in front of a car on the South Unit Scenic Loop.Farragutful

Feral horse at a glance

Equus ferus caballus FEH-rul horse; Equus ferus caballus is EK-wus FEH-rus kuh-BAL-us

Type
Mammal · horse
Diet
Herbivore
Size
Horses run from about 500 pounds to nearly 2,000 depending on the breed, and the park's horses trace back to Quarter Horse, Paint, and draft stock. A full-grown one outweighs a grown-up several times over, and its back is above the top of your head.
Lifespan
A horse commonly lives about 25 to 30 years. Nothing here feeds or doctors these ones, and foals are the animals most likely to die young: park records show 3 to 9 foal deaths in a normal recent year.
Conservation
Not applicable. A domestic animal living loose, not a wild species, so wildlife rankings do not apply to it.

Eats prairie grasses, sedges, whatever green is closest to the road

Horses graze low and steadily, cropping grass with their front teeth. NPS counts them carefully because inside a fenced park they eat the same forage as the bison, elk, and pronghorn.

Should you worry?

Yes, keep your distance. These are not tame and not trained, and a horse that feels crowded kicks or bites. NPS asks visitors not to feed, chase, or approach them, and recommends binoculars instead. Stay in the car when a band crosses the road, the same rule as for bison.

Somewhere on the South Unit Scenic Loop the grass moves and it is not bison. Six or eight horses stand on a slope above the road, one of them watching you and the rest eating. They look like horses in a pasture, because that is what their great-grandparents were.

These are not a wild species. A horse is Equus ferus caballus, the domestic horse, and NPS says so plainly: free-roaming horses on the Great Plains are commonly called wild, but the correct designation is feral, since they descend from domesticated animals. Feral means loose and untended. Wild means never domesticated in the first place. The difference is a family history, not a personality.

Ranchers here turned horses out on open range to live and breed, then gathered them when they needed a saddle horse. A roundup in 1954, after the park was fenced, took out 200 branded animals. A few small bands dodged the roundup, went unclaimed, and stayed. For several years the Park Service tried to remove them too. Then in 1970 park policy changed to recognize the horse as part of the historical setting, and the horses became what NPS calls a historic demonstration herd: livestock kept to hold a cultural scene, in this case the open range Theodore Roosevelt rode through in the 1880s.

Being livestock instead of wildlife has consequences. The 1971 Wild Free-Roaming Horses and Burros Act protects free-roaming horses on Forest Service and Bureau of Land Management ground, and not these. Genetic work on the herd points to Quarter Horse, Paint, and draft breeds rather than the Spanish stock behind the mustang story. And the park counts them: about 198 horses in early 2026, against a population goal of 35 to 60 head written into a 1978 environmental assessment. Since 2020 every mare over 8 months old has been given the immunocontraceptive GonaCon Equine, usually by dart.

In 2024 a draft NPS plan proposed removing the herd. More than 19,000 pieces of public correspondence came in during one scoping period, opposition kept up, and the Park Service terminated the removal plan in April 2024. Management continues under the 1978 goal of 35 to 60 head: a roundup that October brought horses into the South Unit corrals, none left the park, and GonaCon goes on. What nobody has set is a number — NPS says there is no target herd size yet.

What you can do from the road is look for the mailbox before you look for the horse. A stallion drops manure in the same spot again and again to mark his band’s ground, and those stud piles sit right along the drive. Find a fresh one, then scan the ridge above it.

Did you know?

  • A stallion marks his band's ground by dropping manure in the same spot again and again. NPS calls these stud piles, and they sit right along the scenic drive, so you can sometimes find horses by finding their mailbox.
  • When a stallion moves his mares, he lowers his head and neck almost to the ground and drives them forward. The move has a name: snaking.
  • In 2024 an NPS draft plan proposed removing the South Unit's roughly 200-head horse herd. Sustained public and political opposition forced the Park Service to halt the removal plan in April 2024, and the herd's future is unresolved.
  • Genetic studies on the park herd found relationships to Quarter Horse, Paint, and draft breeds, and no clear connection to the Spanish horses people usually picture when they hear the word mustang.

Common questions

Are these wild horses?

No, and the park is direct about it. NPS writes that free-roaming horses on the Great Plains are commonly called wild, but the correct designation is feral, because they descend from domesticated animals. These horses are the offspring of ranch horses that ranchers turned out on the open range before the park was fenced.

Then why does the park keep them?

For a while it did not. The Park Service tried for years to remove every horse. In 1970 park policy changed to treat the horse as part of the historical setting, and the horses have been managed since then as a historic demonstration herd standing in for the open-range ranching era Roosevelt knew.

Where in the park do we look?

The South Unit near Medora. Bands range across the scenic loop country and are often visible from Painted Canyon Overlook, from Buck Hill, and from I-94 along the park boundary. The North Unit has no horses; its demonstration livestock is a small herd of longhorn steers.

How many horses are there?

About 198 in early 2026, by an NPS collar study that tracked 15 mares. The park's population goal, set in a 1978 environmental assessment, is 35 to 60 head, and closing that gap is what the arguments are about.

Why does the park vaccinate the mares?

To slow the number of foals born without rounding up and hauling away horses. Since 2020 female horses over 8 months old have received the immunocontraceptive GonaCon Equine, delivered by dart or by hand injection. It is not permanent, and foals are still born.

Where it lives

Where we got this