Wild Horse and Burro On-Range Population Estimates

As required under the Wild Free-Roaming Horses and Burros Act of 1971, the BLM conducts an annual population inventory to estimate the number of wild horses and burros roaming BLM-managed lands in the West. To promote healthy conditions on the range, the BLM determines what it calls the Appropriate Management Level (AML), which is the number of wild horses and burros that can thrive in balance with other public land resources and uses. Wild horses and burros that exceed AML (which is 26,785) are to be removed from the range, in accordance with the 1971 law, as amended. The current estimated on-range wild horse and burro population (as of March 1, 2021) is 86,189 animals. 

For further details on BLM population estimates, download the complete 2021 HA and HMA Dataset (pdf). 

Land Managed for Wild Horses and Burros

In 1971, when Congress passed the Wild Free-Roaming Horses and Burros Act, these animals were found roaming across 53.8 million acres of public land, known as Herd Areas, of which 42.4 million acres were under the BLM’s jurisdiction. Today, the BLM manages wild horses in subsets of these Herd Areas, known as Herd Management Areas (HMAs), that comprise 31.6 million acres.  (For an explanation of "What happened to the 22.2 million acres?" see the response to Myth #4 on the Myths and Facts page.) Under the 1971 Act, horses and burros may not be re-located to other public lands where they were not found roaming when the law was passed.

Population Growth Suppression Treatments

In 2013, the National Academy of Sciences (NAS) reported that no highly effective, easily delivered and affordable fertility-control methods were then available to manage wild horse and burro population growth on the range. The NAS also urged the BLM to research new, longer lasting methods. Three fertility control vaccines that BLM uses today in wild horse management were among the methods that the NAS report identified as most promising in 2013. “ZonaStat-H” is the most widely used form of porcine zona pellucida (PZP) vaccine. It can be injected by hand or deployed via ground-darting, however, is generally effective for only one year. “PZP-22” is a second form of PZP vaccine; one dose can lead to moderate effects that may last two years. A follow-up dose of PZP vaccine in a mare that already received PZP-22 can cause somewhat stronger effects for up to three years. “GonaCon-Equine” is the third contraception vaccine BLM uses for management, and it can be delivered by hand or by dart. One dose of GonaCon can cause moderate effects that may last two years, but a second dose can cause high rates of contraception that may last 4-5 years. In many herds where wild horses are approachable, BLM gets valuable help from volunteers who devote many hours to identifying animals and delivering vaccines by dart. Unfortunately, delivering any vaccine via dart is not a viable option for most wild horse herds because the animals tend to avoid human contact and the vast sizes of most herd management areas make it difficult to locate and approach individual horses.  

Wild Horse and Burro Removals

Wild horses and burros have virtually no natural predators and their herd sizes can double about every four years. As a result, the BLM removes thousands of animals from the range each year as part of its efforts to control herd sizes. 

*Includes 2 mules

Wild Horses and Burros Adopted into Good Homes

The BLM offers wild horses and burros that were removed from the range for adoption into private care. Since 1971, the BLM has adopted out more than 250,000 wild horses and burros nationwide. Potential adopters can attend an off-site adoption event, visit a BLM adoption center, or participate in an Internet Adoption event. For general questions on adopting a wild horse or burro, visit the Frequently Asked Questions page.  

Wild Horses and Burros Sold to Good Homes

About 8,400 wild horses and burros immediately became eligible for sale under the December 2004 sale-authority law (the so-called "Burns Amendment"), which directs the BLM to sell "without limitation" to any willing buyers animals that are either more than 10 years old or have been passed over for adoption at least three times. Since 2005, the BLM has sold more than 5,900 horses and burros. It has been and remains the policy of the BLM, despite the unrestricted sales authority of the Burns Amendment, NOT to sell or send any wild horses or burros to slaughterhouses or to "kill buyers." Learn more about the Sales Program. 

* In addition to sales totals, 7 animals were transferred to other government agencies. 

** Includes 3 wild horses transferred to other government agencies

Number of Wild Horses and Burros Trained

In an effort to place more animals into private care, the BLM partners with non-profit organizations, volunteers, and state and county prisons to train wild horses and burros prior to being placed into a good home. Trained animals tend to have a higher rate of adoption by the public than untrained.

*Includes one mule

Populations of Wild Horses and Burros in BLM's Off-Range Facilities
(as of June 2021)

All off-range (unadopted or unsold) wild horses and burros, like those roaming Western public rangelands, are protected by the BLM under the 1971 Wild Free-Roaming Horses and Burros Act, as amended. These off-range horses and burros are fed and cared for in either off-range corrals or pastures at a cost of nearly $50 million a year. The BLM maintains a monthly holding facilities report, which can be found by clicking on the Public Lands Stats tab below. Access the most recent FY2021 monthly facility report. The total capacity of all BLM off-range holding facilities is 68,717 animals. 

Wild Horse and Burro Program Budget

FY2020

FY2019

FY2018

FY2017

FY2016

FY2015

FY2014

FY2013

FY2012

* Expenditures include funding sources from multiple program areas related to wild horse and burro management.

Historical Program Data and Public Lands Statistics

This table contains links to data related to on-range population of wild horses and burros, adoptions and removals by fiscal year.  Some data are preliminary and subject to revision before the end of the fiscal year. Download prior year wild horse and burro accomplishments fact sheets: FY2018 and FY2019.