The Wild Free-Roaming Horse and Burro Act recognizes the wild horse as an “integral component of the natural system.” It stipulates that horses can only be removed from public lands if it is proven that they are overpopulating or are causing habitat destruction. It further mandates that the government “maintain specific ranges on public lands as sanctuaries for their protection and preservation.”
The horse’s digestive system does not thoroughly degrade the vegetation it eats. As a result, it tends to “replant” its own forage with the diverse seeds that pass through its system undegraded. This unique digestive system greatly aids in the building up of the absorptive, nutrient-rich humus component of soils. This, in turn, helps the soil absorb and retain water upon which many diverse plants and animals depend. In this way, the wild horse is also of great value in reducing dry inflammable vegetation in fire-prone areas. Back in the 1950s, it was primarily out of concern over brush fires that Storey County, Nevada, passed the first wild horse protection law in the nation.
The fact that horses wander much farther from water sources than many ruminant grazers adds to their efficacy as fire preventers. This tendency to range widely throughout both steep, hilly terrain and lower, more level areas, while cattle concentrate on lower elevations, also explains why horses have a lesser impact on their environment than livestock: unlike cattle that will camp on and destroy a riparian area, a wild horse herd will water in a quick and orderly fashion, then move on to highland grazing areas rarely frequented by cattle; unlike cows, horses do not defecate in the water.
Horses have also proven useful to other species they share the range with: in winter months, they open up frozen springs and ponds with their powerful hooves, making it possible for smaller animals to drink. Another positive effect of wild horses on biodiversity was documented in the case of the Coyote Canyon horses in the Anza Borrega National Park (California). After wild horses were all removed from the Park to increase big horn sheep population, bighorn sheep mortality actuality skyrocketed: mountain lions – wild horse predators – compensated the loss of one of their prey species by increasing their predation on other species.
More information on the specie and its issues through the pages of The American Wild Horses Preservation Campaign.