Do Wild Horses Reduce Wildfire Risk? An Assessment of the Scientific Evidence

One of the most widely promoted arguments for keeping or expanding wild horse populations is that they reduce wildfire risk. A concept presently gaining popularity in its application to wild horses for wildfire mitigation on public lands is that proposed by Captain William E. Simpson II (Simpson, n.d.), a retired U.S. Merchant Marine and commercial airline pilot who resides on the California–Oregon border. Simpson has years of observation of a free-roaming band of wild horses that reside on his property and has developed a proposal called the ‘Wild Horse Fire Brigade‘ (Simpson, n.d.). Simpson’s fire-controlling concept lacks academic research backing in fields such as ecology, wildlife management, rangeland ecology and management, silviculture and fire ecology. Even though an interesting concept, it lacks substantial data from replicated studies that have been subject to peer review, published in credible scientific journals, and applicable in the North American context (O’Neill, 2022).

While transferring thousands of wild horses from BLM holding facilities to spread across wildland fires on remote Federal Forests and Wilderness Areas for year-round grazing on the very fuels that the horses are to consume to reduce future wildland fires on public and private lands. This idea may garner the attention of the public and the enthusiasm of wild horse advocates as a management hypothesis; there is no study or data that support the use of free-roaming feral horses for the purpose of reducing the frequency and total area burned of individual wildfires, as well as the costs of fire suppression in North America.

In evaluating evidence for the role of wild horses in reducing fuels and fire, the great majority of scientific work has focused on horses in managed grazing systems (as contrasted with unmanaged feral horses) across a variety of Mediterranean ecosystems. These studies find that, under certain conditions and with management of key factors such as stocking rate, horses can reduce grass height and, on the ground surface, consume fine fuels. But they also find that horses have relatively little impact on woody plants of any kind and that the effect of horses in reducing fuels to reduce fire is site-specific, depending greatly on the intensity of horse grazing and the number of horses present on the ground. Finally, these studies of horses in Mediterranean-type ecosystems with managed grazing note that, in no case, do horses alone provide sufficient fuel reduction to mitigate wildfire. Horses must be part of a combination of grazing animals, including cattle and browsers, along with prescribed fire and mechanical fuel treatment (Rigueiro-Rodríguez et al. 2012; Janeiro-Otero et al. 2024; Ribeiro et al. 2025; Gort-Esteve et al. 2025).

In studies in Mediterranean regions, such as Galicia and Portugal, horses of all categories (feral, semi-domesticated and domestic) are managed as part of a landscape, within fenced areas such as gorse heathland with scrub and grasses. In contrast, fuels in wildland fires in western North America consist mainly of drought-stressed shrubs and trees such as sagebrush, pinyon-juniper, and other woody species, as well as perennial and annual grasses, including cheatgrass, and many other fuel types. Such large, long-duration wildland fires are influenced by a complex array of factors, including drought, wind, the persistence of continuous fuels, topography, and weather over extended periods. Such fires cannot be managed by a single variable, such as wild horses grazing.

The largest fires in recent years have burned in the very same HMAs where wild horses reside. After the 285,000-acre 2015 Soda Fire burned the entire Hardtrigger and Sand Wash Basin HMAs and portions of the Black Mountain HMA, BLM staff spent months gathering wild horses from the Hardtrigger HMA to manage them in holding facilities for emergencies, as the forage in that huge area had been burned to the ground. In 2024, the Jump Fire burned much of the Sands Basin and Four Mile HMAs, and an emergency gather was conducted for the thousands of wild horses dispersed across those burned areas to reestablish a stable, healthy wild horse population with suitable forage. Similarly, after the 2012 Jakes Fire burned a huge section of the Snowstorm Mountain and Little Humboldt HMAs, the wild horses from those HMAs were managed from the holding facilities for several years as the forage that existed in that area was severely reduced and burned to the ground, and it took many years to reestablish. This same management has occurred following other major fires in the Fox and Lake Range, Three Fingers, and Centennial HMAs.

In addition, the use of the Salt River horses in Arizona as an example of wild horses performing natural fire control has been debunked by fires within the horses’ home range and beyond that required fire suppression by agencies. Examples of these fires include the 2017 Cactus Fire, the 2020 Dome Fire, the 2020 Christmas Fire, and the 2024 SR-87 Fire.

While horses do impact the landscape and specific fuels within it, the extent to which they might affect potential wildfire and resulting behaviour is typically localised. The extent of that impact would be significantly influenced by various management factors, including the availability of forage for the horses.

In summary, there is no scientific basis to support the use of free-roaming feral horses as a meaningful component of the landscape for mitigating wildfire. Additional well-designed studies are needed to determine specific reductions in fuel use, resulting changes in fire behaviour, and subsequent impacts on the number and size of individual wildfires in climates, environments, and ecologies similar to those of the American West. Until such time, the Wild Horse Fire Brigade remains an untested fire management hypothesis.

References

Bureau of Land Management. (2015). Soda Fire Wild Horse Gather.

Bureau of Land Management. (2016). Three Fingers Emergency Wild Horse Gather.

Bureau of Land Management. (2020). Centennial Herd Management Area Gather.

Bureau of Land Management. (2023). Fox and Lake Range Emergency Wild Horse Gather.

Bureau of Land Management. (2024). Sands Basin and Four Mile Emergency Wild Horse Gather.

Bureau of Land Management. (2026). Jakes Fire Emergency Wild Horse Gather.

Gort-Esteve, A., Bartolomé Filella, J., Roselló Molinero, X., Torra Burgués, A., Riera, J. L., & Nieto-Espinet, A. (2025). Dietary strategies of feral and domestic horses under varying grazing pressures: Insights for Mediterranean forest management. Agroforestry Systems, 99, 208.

Janeiro-Otero, A., Álvarez, X., & Dormann, C. F. (2024). Application of remote sensing to understand the role of Galician feral horses in the biomass reduction of a shrub-grassland-dominated landscape. BMC Ecology and Evolution, 24, 89.

O’Neill, S. (2022, October 23). Meet the man who says wild horses could help prevent the next wildfire. NPR.

Ribeiro, I., Aliácar, S., Domingos, T., McCracken, D., & Proença, V. (2025). Semi-wild horse grazing as a rewilding strategy: Assessing effects on vegetation structure and composition in the Côa Valley, Portugal. Frontiers in Ecology and Evolution, 13, 1596560.

Rigueiro-Rodríguez, A., Mouhbi, R., Santiago-Freijanes, J. J., González-Hernández, M. P., & Mosquera-Losada, M. R. (2012). Horse grazing systems: Understory biomass and plant biodiversity of a Pinus radiata stand. Scientia Agricola, 69(1), 38–46.

Simpson, W. E., II. (n.d.). Wild Horse Fire Brigade advocacy materials.