The BLM protects, manages, and controls wild horses and burros on public lands under the authority of the Wild Free-Roaming Horses and Burros Act of 1971 to ensure that healthy herds thrive on healthy rangelands. The following subject guide provides information on the BLM's wild horse and burro program, and on wild horses and burros in general, and is intended as a starting point for researchers.
More information about the BLM’s wild horse and burro program can be found on the program's website. Questions about the program can be addressed to email@example.com or by calling (866) 4MUSTANGS [(866) 468-7826].
For questions about this guide or assistance accessing resources presented here, please contact firstname.lastname@example.org. We also appreciate your feedback and suggestions for this subject guide.
This subject guide includes:
Scientific Literature | Legislation | BLM Publications | Instruction Memoranda | Links of Interest | Video
BLM librarians have compiled a bibliography of publications relevant to wild horses and burros. Links are provided where available but access may be limited to BLM employees due to our subscription agreements. For assistance locating any of these publications, including those not available online, BLM employees should contact email@example.com.
On our website, links to journals held by the BLM Library are organized alphabetically by title and by subject. Articles relevant to wild horses and burros are likely to be found in journals on our ecology, range, and wildlife lists.
View digitized BLM publications on either of these sites:
Learn more about the BLM Library's large-scale digitization effort.
U.S. Department of the Interior, Bureau of Land Management, and U.S. Department of Agriculture, Forest Service. 1997. The 10th and 11th report to Congress on the administration of the Wild Free-Roaming Horses and Burros Act for fiscal years 1992-1995. Washington, D.C.
A series of 13 Resource Notes (numbers 23 through 35) were published by BLM based on transactions from the Wild Horse and Burro Population Viability Forum, a BLM-sponsored event held in Fort Collins, Colorado, on April 21, 1999. They are listed here in reading order:
Coates-Markle, L. 2000. Wild horse and burro population viability. U.S. Department of the Interior, Bureau of Land Management. Resource Notes No. 23.
Moehlman, P.D. 2000. Conservation issues for wild zebra, asses, and horses in Africa and Asia. U.S. Department of the Interior, Bureau of Land Management. Resource Notes No. 24.
Sponenberg, D.P. 2000. Deciding which feral horse populations qualify as a genetic resource. U.S. Department of the Interior, Bureau of Land Management. Resource Notes No. 25.
Jenkins, S.H. 2000. Density dependence in population dynamics of feral horses. U.S. Department of the Interior, Bureau of Land Management. Resource Notes No. 26.
Cothran, E.G. 2000. Genetic variation in horse populations. U.S. Department of the Interior, Bureau of Land Management. Resource Notes No. 27.
Ryder, O.A. 2000. Genetic management of small populations: The special case of feral horses. U.S. Department of the Interior, Bureau of Land Management. Resource Notes No. 28.
Singer, F.J., and L. Zeigenfuss. 2000. Genetic effective population size in the Pryor Mountain wild horse herd: Implications for conservation genetics and viability goals in wild horses. U.S. Department of the Interior, Bureau of Land Management. Resource Notes No. 29.
Noon, B., F. Sampson, and N. Johnson. 2000. Population viability analysis: General principles and applications. U.S. Department of the Interior, Bureau of Land Management. Resource Notes No. 30.
White, G.C. 2000. Methods to collect required data to develop rigorous population viability analysis (PVA) models. U.S. Department of the Interior, Bureau of Land Management. Resource Notes No. 31.
Singer, F.J., and R. Osborne. 2000. Development and assessment of tools that managers could use to monitor wild horse populations. U.S. Department of the Interior, Bureau of Land Management. Resource Notes No. 32.
Underwood, H.B. 2000. Viability of feral horse populations on Atlantic coastal barrier islands: Implications for management. U.S. Department of the Interior, Bureau of Land Management. Resource Notes No. 33.
Gross, J.E. 2000. Effects of contraception and removal treatments on Pryor Mountain wild horse population demographics and genetics. U.S. Department of the Interior, Bureau of Land Management. Resource Notes No. 34.
Coates-Markle, L. 2000. Summary recommendations, BLM Wild Horse and Burro Population Viability Forum, April 21, 1999. U.S. Department of the Interior, Bureau of Land Management. Resource Notes No. 35.
Also see our wild horse and burro bibliography.
Wild Horse Protection Act of 1959, also known as the "Wild Horse Annie Act” (Public Law 86-234)
This was the first federal legislation to protect wild horses and burros. Prohibited the use of a motor vehicle to hunt, for the purpose of capturing or killing, any wild horse, mare, colt, or burro running at large on public lands. Also prohibited the pollution of watering holes on public lands for the purposes of trapping, killing, wounding, or maiming any of these animals.
Wild Free-roaming Horses and Burros Act of 1971 (Public Law 92-195)
Protected wild free-roaming horses and burros from capture, branding, harassment, or death and stated that wild horses and burros were to be considered an integral part of the natural system of the public lands in the areas where they are found. Read the original text or the amended text, as compiled by BLM.
Kleppe v. New Mexico, 426 U.S. 529 (1976)
The U.S. Supreme Court ruled that free-roaming horses and burros are wildlife and it rejected New Mexico's view of the Property Clause of the U.S. Constitution.
Federal Land Policy and Management Act of 1976 (Public Law 94-579)
The Wild Free-roaming Horses and Burros Act of 1971 was amended by the Federal Land Policy and Management Act of 1976 (FLPMA) and later by the Public Rangelands Improvement Act of 1978 (see below). Among its provisions, FLPMA established the BLM and allowed for the Secretaries of the Interior and Agriculture to use or contract for the use of helicopters and motorized vehicles for the purpose of managing wild horses and burros on public lands.
Public Rangelands Improvement Act of 1978 (Public Law 95-514)
The Public Rangelands Improvement Act of 1978 (PRIA) amended the Wild Free-roaming Horses and Burros Act of 1971 and the Federal Land Policy and Management Act of 1976. It established a commitment to inventory and identify current public rangeland conditions and trends while managing, maintaining, and improving the condition of public rangeland. PRIA continued the policy of protecting wild free-roaming horses and burros from capture, branding, harassment, or death, while at the same time facilitating the removal and disposal of excess wild free-roaming horses and burros which pose a threat to themselves and their habitat and to other rangeland values. PRIA also stated that the United States shall receive fair market value for the use of the public lands and their resources unless otherwise provided for by law.
United States v. Johnson, 685 F.2d 337 (9th Cir. 1982)
The Wild Free-roaming Horses and Burros Act was challenged in court for being unconstitutionally vague and overbroad. This decision from the U.S. Court of Appeals, Ninth Circuit, affirmed a conviction under the act and upheld the act.
Mountain States Legal Foundation v. Hodel, 799 F.2d 1423 (1986)
Ranchers argued that wild horses grazing on private property constituted a taking and they should be compensated for it under the Fifth Amendment. The United States Court of Appeals for the Tenth Circuit stated that a wild animal was not an agent of the federal government and could not be found guilty of taking ranchers' leased grass or water. DOI users can access text of the decision via HeinOnline. A law school explanation of the decision in simple language is publicly available.
Animal Protection Institute v. Hodel, 671 F. Supp. 695 (1987)
The Animal Protection Institute and the Fund for Animals sued the Department of the Interior, arguing that BLM was turning a blind eye to the intent to slaughter adopted horses. The court ruled in favor of the Animal Protection Institute, with the condition that BLM would require individuals adopting wild horse and burros to sign an affidavit stating they have no intent to sell the animals for slaughter or for use as rodeo stock.
Omnibus Parks and Public Lands Management Act of 1996
Authorized BLM and the USDA Forest Service to use helicopters and motor vehicles to round up and transport feral horses on public lands.
Fund for Animals v. Babbitt, Case No. CV-R-85-365-HDM (D. Nev. settlement approved, Oct. 14, 1997)
Requires prospective adopters to sign a private maintenance and care agreement, under penalty of perjury, that they are not adopting animals for slaughter or other commercial use.
Instruction Memoranda (IMs) are limited-scope policy documents issued by BLM for internal direction. The following list includes IMs issued by the BLM Washington Office (WO) from fiscal year 2010 to present.
Gelding of Wild Horses and Burros
Exception to Policy in BLM Handbook H-4700-1 and Manual 4720.41: “Helicopter Gather of Wild Horses and Burros between March 1 and June 30”
Comprehensive Animal Welfare Program for Wild Horse and Burro Gathers
Animal Health, Maintenance, Evaluation and Response
Required Timelines and Naming Conventions for Entering Data into the Wild Horse and Burro Program System and Recording/Reporting Requirements for Other Data
Guidance for the Sale of Wild Horses and Burros
Resource Management During Drought
Wild Horse and Burro Gathers: Internal and External Communicating and Reporting
Wild Horse and Burro Gathers: Management by Incident Command System
Wild Horse and Burro Gathers: Comprehensive Animal Welfare Policy
Wild Horse and Burro Gathers: Public and Media Management
WO IM-2013-032 - superseded by WO IM-2014-132
Direction for the Sale of Wild Horses and Burros – Interim Guidance
WO IM-2013-019 (INTERNAL)
Wild Horse and Burro Herd Area and Herd Management Area Data Standard. For internal use only; access is limited to users on the BLM network.
New Program Measures and Elements
FY 2012 “Director’s Challenge”: Expanding Volunteer Engagement in Monitoring and Sustaining the Health of BLM Wild Horse and Burro Herd Management Areas
Protocols for Media at Wild Horse and Burro Gathers
The Bureau of Land Management’s (BLM) Partnership with the Mustang Heritage Foundation
Helicopter Capture of Wild Horses and Burros
Public Observation of Wild Horse and Burro Gathers
Wild Horse and Burro Gather Daily Reporting Policy, Internal Communications Protocols
Gather Policy, Selective Removal Criteria, and Management Considerations for Reducing Population Growth Rates
WO IM-2010-130, Change 1
Wild Horse and Burro Gather Decisions
WO IM-2010-130 - see also WO IM-2010-130, Change 1
Wild Horse and Burro Gather Decisions
Links of Interest
U.S. Department of the Interior, Bureau of Land Management: Wild horse and burro program
This site provides history of wild horses and burros, recent news, information on adoption, gathering schedules, links to each participating state program, as well as myths and facts.
U.S. Department of the Interior, Bureau of Land Management: Wild horses and burros news and information
This site contains current news information regarding BLM and its wild horse and burro program.
Saint Louis Zoo: AZA Wildlife Contraception Center
This site shares information regarding wildlife contraception, including information about specific contraception products. In particular, see the Contraception Methods page and follow links for "Porcine Zona Pellucida Vaccine" and "Perissodactyls" (which includes equids). Although this site is from a zoo perspective, contraceptive research is directly applicable to management of wild populations.
The Science and Conservation Center at ZooMontana
An independent non-profit organization that is the only dedicated facility for the development of wildlife contraceptives and methods of application, the Science and Conservation Center (SCC) produces and distributes porcine zona pellucida (PZP). The site offers an FAQ page, general information about PZP, and a publications page. The SCC produces extensive research on immunocontraception, led by Dr. Jay Kirkpatrick. We have included many of his papers in our wild horse and burro bibliography.
PNC, Inc.: Wildlife fertility control
An excellent resource for information on porcine zona pellucida (PZP), a widely-used immunocontraceptive vaccine, this site is produced by PNC, Inc. (Pity Not Cruelty) a not for profit foundation. This site discusses the origins of PZP, answers FAQs, and provides other resources, including a bibliography. Of special note are the links along the left side of the PZP: Fact & Fancy page. Although the site appears not to have been updated recently, the information presented is still valid.
Greater Yellowstone Science Learning Center: Wild horses
The National Park Service has developed Research Learning Centers as public-private partnerships that encourage the sharing of scientific information about the parks, facilitate research efforts, and provide opportunities for the public to learn about the national parks. This site offers information about the unique Spanish population of horses that reside in the Pryor Mountains (Montana) as well as a list of selected references.
The Humane Society of the United States: Wild horses
Includes news and events as well as reports, fact sheets, and other resources.
National Mustang Association, Inc.
Focusing on wild horses in Utah, this site gives an overview of wild horse issues, where to view wild horse herds, and how to "adopt a horse for a year" to support wild horses kept at the National Mustang Ranch in Barclay, Nevada.
Video: The Story of America's Wild Horses and Burros
Produced by the Bureau of Land Management and released in May 2012, this video outlines the history of how the BLM came to manage federally protected wild horses and burros on millions of acres of public lands across the West. Current and former BLM employees, historians, horse advocates, and others tell their parts of this continuing story.
Click to watch the video on YouTube (running time 56:28).
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