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Based on an article in Science & Children Magazine, Published by the National Science Teachers Association, May 2001

Dawn of an American Legend

Spanish explorers and missionaries brought the first modern horses (Equus caballus) and burros (Equus asinus) to the New World in the 16th century. Today's North American free-roaming horses and burros are descendants of those domestic animals and of later animals that escaped—or were released— from captivity. They are therefore technically described as feral—descended from domestic animals, but no longer under human control. However, the term wild has become generally accepted in nonscientific use. Free-roaming horses of Spanish ancestry are also referred to as mustangs, a term that came into use in the early 1800s and is Americanized slang for the Spanish word mesteño, meaning "stranger."

Roaming the West

Today, American wild horses and burros are located primarily in remote portions of the West, with much smaller populations of horses also living on barrier islands off the mid-Atlantic coast.

Most western herds are managed by the Bureau of Land Management (BLM) within about 200 herd management areas (HMAs) located in 10 western states. In total, BLM manages an estimated 40,000 horses and 5,000 burros roaming 17.4 million ha of public and private lands. Half of these animals are located in Nevada. Far smaller numbers of horses are managed by the U.S. Forest Service, the National Park Service, the Department of Defense, and tribal and state governments.

In the West, wild horses inhabit arid grasslands and semidesert shrublands, but may also be found in piñon-juniper woodlands with an understory of grasses. Grasses, such as Indian ricegrass (Oryzopsis hymenoides) and western wheatgrass (Agropyron smithii), are their forage of choice. During the winter, wild horses depend on a variety of shrubs and in times of heavy snowfall will even eat the sprigs and bark of trees. Each day, the average wild horse eats about 11 kg of food and spends an average of 12 hours grazing.

Banding Together

Wild horses live in tightly knit bands— family groups comprised of one stallion (male), a lead mare (female), and subordinate mares with their foals (offspring less than a year old). Average band size in most HMAs is about seven horses, though this number is highly variable. in a particular area.

Wild horses have a better chance of seeing and escaping predators and of finding scarce food if they live together. As social creatures, horses communicate primarily via body language, such as ear, head, and neck movements. Other important communication methods are scent sniffing, neighing, squealing, snorting, other vocalizations, foot stomping, and kicking. Mutual grooming probably both feels good and serves to reduce tension and reinforce bonds between these powerful, large mammals.
A wild horse finds an abundant supply of wild grasses, its favorite food.
In southern Nevada's Spring Mountains– named for their plentiful springs–a wild horse finds an abundant supply of wild grasses, its favorite food.

The dominant mare leads the group in its daily routine of grazing and watering on the band's home range and also decides the direction and course of band movement. The lead stallion's role is to protect his band from danger, keep the band together, prevent rival males from stealing his harem of mares, expand his harem, and sire new foals.

The peak foaling period is in spring. Young stallions are normally driven from the maternal band at the age of two years or less. By encouraging their offspring to leave the band, wild horses avoid inbreeding. Banished adolescents continue to follow the band at a distance until they find other ousted young males with which they form bachelor bands. Between the ages of four and eight, a bachelor stallion is usually able to acquire and hold a harem of his own.

With the elimination of wolves in most areas of the West, the mountain lion (Puma concolor) tends to present the

Wild Horse and Burro Herd Management Areas

Map showing the distribution of wild horses

Most wild horses and burros in the United States are found in 10 western states in about 200 distinct herd management areas, shown here in green. The Bureau of Land Management is responsible for managing some 45,000 wild horses and burros on public lands.

photo of two wild horses
In a band of wild horses, the lead mare–in this case, the pinto–plays an important role. Besides directing the band's daily wanderings in search of food and water, she also keeps the other horses in line.


largest nonhuman predator threat to wild horses. However, mountain lions do not range sufficiently or exist in large enough numbers to have a significant effect in checking herd growth in the West.

Built to Endure

Individual wild horses are relatively compact, ranging in height from 13 to 16 hands (1.3 to 1.6 meters at the shoulder) and weighing from 315 to 450 kg, with heavy muscles, a large lung capacity, short back, full mane, and low-set tail. They have acute hearing and are able to rotate their ears approximately 180° to capture sounds. Their eyes can move independently and are placed in such a manner to allow them a 320° field of view, even while grazing head-down.

As a result of rigorous environmental demands and adaptive growth patterns, they possess stronger legs, higher bone density, and harder hooves than do domestic horses. Wild horses attain their full growth between the ages of four and seven years, though horses are considered mature at five years old, when they have attained their full complement of permanent teeth. In the wild, horse life-spans average 20 years.

Wild horses come in an almost endless variety of colors, including dun, grulla (a deep steel blue), blue roan, buckskin, pinto (paint), and white, though most are bay or brown. Several of today's recognized pure-bred horse lines have been developed from American wild horses, including the Quarter Horse and color breeds such as the Appaloosa and Palomino.

Long-Eared Survivors

Wild burros, also known as donkeys and jackasses, range throughout all of the North American hot deserts and can live in various harsh habitats as long as they are within 15 km of a water source. They have long ears, a short mane, and can grow to about 1.1 m in height. They vary in color from gray to brown to black.
Originally from Africa, where they are known as wild asses, burros are hardy, surefooted animals that can locate food in almost barren terrain. They can tolerate a water loss of as much as 30 percent of their body weight, and replenish it after only five minutes of drinking. (By contrast, a human who lost even 10 percent of his or her body weight to dehydration would require immediate medical attention and a full day of intermittent drinking for replenishment.)

Wild burros feed on various plants, including grasses, Mormon tea (Ephedra viridis), and palo verde (Parkinsonia L.). They usually forage during the daytime, except during the height of summer.

Female wild burros (jennies) give birth to one offspring each year. Burros do not have a defined breeding season as wild horses do, so foals may be born at any time of the year. Male burros are known as jacks. Since wild burros have few natural predators, competitors, or common diseases, most young burros manage to reach maturity, and may live to more than 30 years of age in the wild. They are so hardy, in fact, that many formerly domestic burros serving as pack animals only became wild after their masters had perished in the harsh desert environment.

Thundering Herds

By the 1800s, more than two million wild horses roamed through western North America. Part of this explosion was due to successful reproduction in the wild. Population growth also resulted from the escape or abandonment of additional domestic horses brought to the frontier by trappers, settlers, miners, and other immigrants. Wild burro herds also increased as individuals of this species escaped from shepherds and miners.
Photo of two wild burros
Most of the approximately 5,000 wild burros on public lands live in Arizona and California, with smaller numbers found in Nevada, Utah, and a few other states. Well adapted to almost barren, nearly waterless terrain, ancestors of modern wild burros served as pack animals for miners and Spanish missionaries.

At the same time, the available open range began to shrink as cattle, sheep, fences, farms, ranches, and roads proliferated. Wild horse numbers began to decline as they were shot to reduce competition with domestic livestock. Tens of thousands were also rounded up for use as draft animals, saddle stock, military mounts, and food. Burros were less persecuted because they tended to graze lands that were too barren and dry for livestock to use.

This downward trend continued into the 20th century but reversed itself briefly during the Great Depression when many horses were abandoned by owners who could no longer afford to care for them. As the century progressed, lucrative European markets for horse meat emerged, as did domestic markets for pet and chicken feed. Wild horses began disappearing in even larger numbers from the western range.
Photo of a mother and foal
The bond between mother and foal is remarkably strong. Shortly before giving birth, a mare usually looks for a secluded spot where she and her newborn remain for several days. On its feet within hours, the foal is soon able to travel with its mother and the rest of the band.
By the 1950s their population was thought to have dropped to fewer than 20,000. In addition, professional mustangers (horse-catchers) often used brutal methods to capture and transport wild horses for sale to slaughter-houses and rendering plants. Public concern developed over falling populations and inhumane treatment of the animals.

A Call to Action

Velma Johnston, a shy, middle-aged secretary from Reno, Nevada, was roused into action one day in 1950 on her way to work. When she noticed blood leaking from the back of a mustanger's truck, she followed the vehicle to a rendering plant. Horrified by her gruesome discoveries there, Johnston began a relentless campaign to save the wild horses.

Photo of Velma Johnston
A shy Nevada secretary named Velma Johnston turned a devotion to animals into a crusade. Johnston's campaign eventually resulted in passage of the Wild and Free-Roaming Horse and Burro Act of 1971.

Nicknamed "Wild Horse Annie" by her detractors, Johnston initiated a letter-writing campaign—her so-called "Pencil War"—that produced more letters to Congress than any single subject except the Vietnam War. Thousands of letters were written by schoolchildren who were concerned for the horses' welfare.
Wild Horse Annie's efforts culminated in the enactment of the Wild Horse Annie Act of 1959 (Public Law 86-234), which was difficult to enforce, and later in the Wild and Free-Roaming Horse and Burro Act of 1971 (Public Law 92-195).

Protecting a "Living Symbol"

The 1971 law sought to preserve wild horses and burros on federal lands as 'living symbols of the historic and pioneer spirit of the West." It placed the animals under federal jurisdiction and imposed criminal penalties for harming them. The law required identification of distinct herd areas where wild horses and burros were living as of 1971, and required federal agencies to manage animals only in those areas. Management responsibility was assigned to BLM within the Department of the Interior and to the U.S. Forest Service within the Department of Agriculture. Wild horses and burros have thrived under federal protection, and the responsibility of land managers to protect the herds and the rangeland has become all the more challenging as issues of science and society intertwine.

Management Challenges

To some people, wild horses and burros are a national legacy, running wild and free. To others, horses are runaways that should be removed from the range altogether. To find common ground, BLM, which cares for most of the wild horses and burros on public lands, consults with various groups and individuals. In addition, a Wild Horse and Burro Advisory Board composed of representatives from multiple interest groups meets regularly to discuss issues and advise the agency. Still, because arguments are complex and multifaceted, BLM faces significant challenges in managing the program.

A Bumpy Ride

BLM strives to manage wild horses and burros as wildland species and not as livestock. Typically, the agency does not feed or water the animals, but does intervene in cases of extreme drought, fire, or freezing weather. When conditions are particularly perilous for the animals, BLM relocates or removes them from the range. For example, in 2000, more than 3,500 animals were removed from the range in response to drought conditions. Wild horse and burro advocates would like BLM to expand efforts to protect the animals through restrictions on livestock and other actions.

The growing population of the West also poses challenges to the management of wild horses and burros. Expanding urban areas are edging up to federally owned rangelands, shrinking wild horse and burro habitat. The animals are now faced with paved highways, power lines, traffic, and homeowners. Cross-fencing and gates used by ranchers to rotate live-stock can also impede herd movements. And, sadly, wild horses and burros are sometimes victims of random shootings despite the fact that these crimes are felonies punishable by significant fines and/or imprisonment.

A Balancing Act

Perhaps the greatest challenge for land managers is determining how many wild horses and burros the land can support without degrading rangelands. The Wild and Free-Roaming Horse and Burro Act directed federal land managers to maintain wild horse and burro populations at levels that ensure a "thriving natural ecological balance." When animal populations exceed the capabilities of their habitat to support them, the land begins to deteriorate. Water quality is degraded and native vegetation damaged, speeding the growth of invasive weeds. When this occurs, animal populations must be reduced to protect rangeland health.

Further complicating the situation, livestock, wildlife, recreational users, and extractive industries, such as timber harvesting and mining, also compete for use

Photo of wild horses and livestock
Wild horses and livestock compete for the same scarce resources of the range. The area around water holes can suffer serious damage when visited by large numbers of horses and cattle.

of the land. Wildlife populations are kept in check through natural predators and hunters. Livestock populations are controlled by federal land managers through limits established in permits issued to ranchers. But controls on wildlife and livestock numbers do not apply to wild horses and burros. They are protected legally from human hunters and have few natural predators. In the absence of these checks, wild horse and burro populations increase, on average, about 15–20 percent each year.

In establishing appropriate wild horse and burro herd levels, land managers consider current herd sizes, rangeland health, and other desired rangeland uses. Wild horse advocates express concerns about genetic diversity: Keeping wild horse population levels too low leaves the animals vulnerable to inbreeding. On the other hand, ranchers want the number of horses reduced because, they assert, horses compete with livestock for limited forage.

BLM is establishing science and technology teams and supporting research to better assess rangeland health and determine appropriate herd management levels. The agency is also expanding partnerships with universities and other groups to obtain census and other data. But these efforts are not likely to quell the debate about how much land should be allocated to wild horses and burros, livestock, and wildlife. Land managers base allocation decisions not only on science but also on public demands for land uses. With so many competing demands for the rangeland, managers must work hard to ensure their decisions reflect a balanced approach.

Exploring the Options

The Public Rangeland Improvement Act of 1978 requires federal agencies to inventory wild horse and burro populations and remove animals exceeding the carrying capacity of the land. BLM has pursued various approaches to controlling herd populations, including fertility control, sanctuaries, and adoptions. Scientists have been searching for methods of birth control for wild mares for a number of years. A time-release vaccine that appears to be effective for one year

with only one shot is being tested on a limited number of mares. Researchers are now working to perfect a vaccine that will last two or three years. While this approach holds promise, it will be years before the vaccine is fully tested. Even when perfected, land managers will have to address the fears of some groups that fertility measures may disturb the genetic viability of herds.

Another approach to the problem of excess animals has been to establish sanctuaries (in most cases on privately owned lands). Federal managers hoped that sanctuaries would eventually be self-sustaining, but admission fees and tourist donations were insufficient to allow these areas to continue without federal support. Nonetheless, sanctuaries are still considered an important management option for older, less easily adopted animals.

Adoptions are the primary method of controlling wild horse and burro populations. Since the early 1970s, approximately 175,000 animals have been adopted by private citizens. Many have become excellent pleasure, show, or work horses.
But the adoption program is not without controversy. Horse advocates are concerned that the timing of gathers can adversely affect mares. Land managers seek to avoid gathers at peak foal times, but debate continues about when this period occurs in each herd area.

The humane treatment of animals during gathers and during their transport to holding facilities also remains a matter of importance to land managers and horse groups alike. Animals are gathered by helicopter or lured with water. Brought close together in confined areas, horses are more susceptible to sickness. And transporting the animals over long distances is stressful. Through employee training, expanded research on wild horse and burro biological needs and social dynamics, and the involvement of partner organizations, BLM is working to ensure that the animals are well treated during all phases of handling.

Even after a wild horse or burro is adopted, BLM continues to face challenges. Although most adoptions are successful, some adopters simply lack the experience to "gentle" their animals, or get them accustomed to the presence of humans and prepare them for riders. In addition, some animals simply will not be gentled. To improve the chances for success, BLM is providing better guidance to adopters and trying to match them with experienced individuals who can serve as mentors. If adopters decide they simply cannot manage a particular animal, the agency will step in to make alternate arrangements for the horse or burro.

One year after signing an adoption agreement, an adopter may receive title to the wild horse or burro provided he or she has properly cared for the animal. At the time of adoption and again when they receive title, adopters are required to sign a statement, under penalty of perjury, indicating that they will not sell the animal for slaughter or use it for bucking in rodeos.

BLM will not issue title if it discovers that an adopter intends to sell the animal for slaughter. Despite these safeguards, some horses for which title has been issued end up in western slaughter-houses. Based on the data provided by American slaughterhouses, BLM program managers believe that the numbers represent only a small percentage of animals removed from public lands. However, the problem is still cause for concern, and measures are being taken to prevent the animals from being slaughtered.

Helicopter being used to gather excess wild horses from a herd management area.
When horse population levels are too high, the rangeland can become degraded and the welfare of the horses is jeopardized. Helicopters are often used to gather excess wild horses from herd management areas. Typically, the horses are herded into a temporary enclosure before being trucked to a holding area at the gather site. Eventually, most will be transported to adoption facilities.


BLM is working with slaughterhouses to track wild horses and burros sent to such facilities. Through an agreement with the U.S. Department of Agriculture's Food Safety and Inspection Service, any horse that shows up at a slaughterhouse with a BLM freeze mark (see foldout) will not be slaughtered unless accompanied by a title of private ownership. Untitled horses identified through this process are repossessed by BLM. If a wild horse or burro is slaughtered soon after the title is transferred, the agency does investigate and seeks prosecution where there is evidence of fraud or perjury. Horse advocates would like to see BLM track adopted animals until their natural deaths to ensure their well being and humane treatment. But once title is issued, the horses and burros are private

A wild horse with a smattering of scars and a show of ribs.
A smattering of scars and a show of ribs give clear evidence of just how tough life on the range can be for wild horses.

property, and BLM maintains that it has no legal basis for interfering in actions or decisions that private owners make with respect to their animals.

Another issue related to the adoption program is the number of animals waiting to be adopted. Many wild horses are maintained in interim facilities until adopters are found. Horse advocates point out that this subjects animals to unnecessary stress and exposes them to disease. They say this problem is exacerbated by the fact that adoptions are declining and the number of animals in holding facilities is increasing. BLM is seeking to counter this trend through better marketing of the adoption program.

The free-spirited animals that inspired countless schoolchildren in the 1950s
Potential adopters inspect horses and burros.
At permanent facilities and temporary adoption sites, such as fairgrounds, potential adopters have plenty of opportunity to inspect the horses and burros and pick out their favorites. Adopters must be over 18 years old, although many parents adopt animals that are then cared for by their children.
will almost certainly gain the allegiance and affection of future generations of Americans. But with the continued growth of communities in the West and the ever-growing demands on public lands, the next generation of land managers will face new challenges to protect wild horses and burros on public rangelands. Meeting these challenges will require an expanded knowledge of wild horses and burros and their ecological systems. It will require the willingness of citizens with divergent views to seek common ground and develop a shared vision for the future. And it will require people like Velma Johnston, who believe that individuals can "make a difference," to find creative solutions and serve as mentors and mediators.