Myth
“It’s either the horses or the land.”
Fact
The goal is healthy horses on healthy rangelands, and the only lasting solutions work with both together.
A clear, at-a-glance view of BLM on/off-the range key management numbers, definitions, and trends, with plain-language context.
Plain-language, evidence-based notes on behavior, on the range of population numbers, how the population is measured and managed, and the legal context, so you can understand what matters and why.
Wild horses are highly social, and understanding herd structure is foundational to informed, humane wild horse management.
Wild horses prefer stable social groups and form long-term affiliative bonds. In free-roaming settings, stallions, mares, and young navigate complex social roles and pressures, and the social environment matters to herd stability.
Management actions that ignore herd structure can affect behavior and movement in ways that shape on-range outcomes over time.
Field note: A herd is more than a headcount. It is a social network with learned behavior and long-term bonds.
The BLM manages the wild horse and burro on-the-range population against a set AML, which is set per Herd Management Area.1,2
The BLM manages the nation’s public lands for multiple uses, in accordance with the 1976 Federal Land Policy and Management Act. The Bureau manages wild horses and burros as part of this multiple-use mandate. The Wild Free-Roaming Horses and Burros Act of 1971 requires the BLM to “determine appropriate management levels” (AML) for wild-free roaming horses and burros on public land areas.2
An AML is specific to wild horses and burros and meant to represent the optimal number that can exist on a given land area. The BLM takes into account a given land area’s resources (such as water). Under the federal Multi-Use Mandate, the BLM must also take into account other authorized. Other uses include cattle grazing rights, which are considered prior to setting AML.3,4,5
AMLs are determined and set after accounting for a land area’s resources, other protected wildlife and cattle grazing rights. Therefore, when the number of wild horses and burros exceed the AML, the BLM will look to reduce the number of wild horses and burros in order to sustain both the land and the availability of grazing for wildlife and cattle.3,4,5,6
Nearly every management decision depends on reliable population counts because population estimates form the basis for all population management decisions.
Population estimates are made in two ways. One way is by using an aerial survey method developed with the U.S. Geological Survey (USGS). We understand that this involves having several observers in the same aircraft independently count herd populations of visible herds in what is called the “simultaneous double-observer method.”7,9
This number is then subjected to a statistical model that estimates how many animals were likely missed and, combined, result in a population estimate for the surveyed herd(s). Where herds are not surveyed, the BLM assumes an annual growth rate of 20%.7,8,9
Wild horses and burros live on approximately 31.6 million acres of public lands across 10 western states. This includes about 26.9 million acres managed by the Bureau of Land Management (BLM) and 4.7 million acres in U.S. Forest Service (USFS) territories.
Tools used to estimate population have direct consequences on population management, which can direct decisions related to land health management and/or wild horse and burro round up.10
Once a population estimate has been made, the BLM reviews whether populations are larger than AML and, if so, makes decisions on how to reduce the population and what population management tools to use.2,4,5,10
Currently, the BLM uses a mix of tools to manage on-the-range wild horse and burro populations. They include: Gathers (also known as Round-Ups) and Fertility Control Tools (FCTs) such as PZP, GonaCon, IUDs.
FCTs require resources to be on the ground and to be able to administer and track treatments and also may require more than one dose, such as darting for PZP and GonaCon. Some FTCs, such as IUDs, require that the animal is in control of the agency to treat directly.4,5,10
View BLM's Tentative Wild Horse and Burro Gather and Fertility Control Schedule (PDF) »
The BLM is required to manage publicly owned lands. They manage hundreds of millions acres that are subject to Mixed Use Mandates, which include AMLs for wild horses on approximately 25.5 million acres, AUMs for cattle under grazing rights on approximately 155 million acres managed by BLM and approximately 93 million acres management by USFS, and all related requirements to keep the land ecologically healthy. This is a huge task with, at times, possibly conflicting interests.3,10,11
The goal is healthy horses on healthy rangelands, and the only lasting solutions work with both together.
The best decisions are scientifically defensible and socially trustworthy. Stewardship insists on both.
You can learn the basics quickly, especially when information is organized around herd life and land health.
Durable outcomes usually come from steady, evidence-based work paired with human respect and long-term follow-through.
The American Wild Horse Foundation is a 501(c)3) charitable organization.
EIN: 47-4925050 • Mailing Address: 2620 Del Monte Lane, Reno, NV 89511
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