Using Science to Improve the
BLM WILD HORSE AND
A WAY FORWARD
Committee to Review the Bureau of Land Management
Wild Horse and Burro Management Program
Board on Agriculture and Natural Resources
Division on Earth and Life Studies
NATIONAL RESEARCH COUNCIL
OF THE NATIONAL ACADEMIES
THE NATIONAL ACADEMIES PRESS
THE NATIONAL ACADEMIES PRESS 500 Fifth Street, NW Washington, DC 20001
NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.
This study was supported by Contract L11PC00058 between the National Academy of Sciences and the Bureau of Land Management. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the organizations or agencies that provided support for the project.
International Standard Book Number-13: 978-0-309-26494-5
International Standard Book Number-10: 0-309-26494-4
Additional copies of this report are available for sale from the National Academies Press, 500 Fifth Street, NW, Keck 360, Washington, DC 20001; (800) 624-6242 or (202) 334-3313; http://www.nap.edu/.
Cover: Design by Michael Dudzik. Horse photo courtesy of the Bureau of Land Management. Burro photo courtesy of Michael Gallagher. Back cover photo courtesy of the Bureau of Land Management.
Copyright 2013 by the National Academy of Sciences. All rights reserved.
Printed in the United States of America
THE NATIONAL ACADEMIES
Advisers to the Nation on Science, Engineering, and Medicine
The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences.
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COMMITTEE TO REVIEW THE BUREAU OF LAND MANAGEMENT WILD HORSE AND BURRO MANAGEMENT PROGRAM
GUY H. PALMER, Chair, IOM,1 Washington State University, Pullman
CHERYL S. ASA, St. Louis Zoo, St. Louis, Missouri
ERIK A. BEEVER, U.S. Geological Survey, Bozeman, Montana
MICHAEL B. COUGHENOUR, Colorado State University, Fort Collins
LORI S. EGGERT, University of Missouri, Columbia
ROBERT GARROTT, Montana State University, Bozeman
LYNN HUNTSINGER, University of California, Berkeley
LINDA E. KALOF, Michigan State University, East Lansing
PAUL R. KRAUSMAN, University of Montana, Missoula
MADAN K. OLI, University of Florida, Gainesville
STEVEN PETERSEN, Brigham Young University, Provo, Utah
DAVID M. POWELL, Wildlife Conservation Society, Bronx Zoo, New York City
DANIEL I. RUBENSTEIN, Princeton University, Princeton, New Jersey
DAVID S. THAIN, University of Nevada, Reno (retired)
KARA N. LANEY, Study Director
JANET M. MULLIGAN, Senior Program Associate for Research
KATHLEEN REIMER, Senior Program Assistant
ROBIN A. SCHOEN, Director, Board on Agriculture and Natural Resources
NORMAN GROSSBLAT, Senior Editor
1 Institute of Medicine
BOARD ON AGRICULTURE AND NATURAL RESOURCES
NORMAN R. SCOTT, Chair, NAE,1 Cornell University, Ithaca, New York (Emeritus)
PEGGY F. BARLETT, Emory University, Atlanta, Georgia
SUSAN CAPALBO, Oregon State University, Corvallis
GAIL CZARNECKI-MAULDEN, Nestlé Purina PetCare, St. Louis, Missouri
HAROLD L. BERGMAN, University of Wyoming, Laramie
RICHARD A. DIXON, NAS,2 University of North Texas, Denton
GEBISA EJETA, Purdue University, West Lafayette, Indiana
ROBERT B. GOLDBERG, University of California, Los Angeles
FRED GOULD, NAS,2 North Carolina State University, Raleigh
GARY F. HARTNELL, Monsanto Company, St. Louis, Missouri
GENE HUGOSON, University of Minnesota, St. Paul
MOLLY M. JAHN, University of Wisconsin, Madison
ROBBIN S. JOHNSON, Cargill Foundation, Wayzata, Minnesota
JAMES W. JONES, NAE,1 University of Florida, Gainesville
A. G. KAWAMURA, Solutions from the Land, Washington, DC
STEPHEN S. KELLEY, North Carolina State University, Raleigh
JULIA L. KORNEGAY, North Carolina State University, Raleigh
PHILIP E. NELSON, Purdue University, West Lafayette, Indiana (Emeritus)
CHARLES W. RICE, Kansas State University, Manhattan
JIM E. RIVIERE, IOM,3 Kansas State University, Manhattan
ROGER A. SEDJO, Resources for the Future, Washington, DC
KATHLEEN SEGERSON, University of Connecticut, Storrs
MERCEDES VAZQUEZ-AÑON, Novus International, Inc., St. Charles, Missouri
ROBIN A. SCHOEN, Director
CAMILLA YANDOC ABLES, Program Officer
KARA N. LANEY, Program Officer
JANET M. MULLIGAN, Senior Program Associate for Research
KATHLEEN REIMER, Senior Program Assistant
EVONNE P. Y. TANG, Senior Program Officer
PEGGY TSAI, Program Officer
1 National Academy of Engineering
2 National Academy of Sciences
3 Institute of Medicine
The above quotation has been translated most commonly as “A journey of a thousand miles begins with a single step” and, alternatively, as “Even the longest journey must begin where you stand.” In both interpretations, there is relevance to moving forward to improve management of free-ranging horses and burros on public lands in the western United States. Although there is a broad spectrum of public opinion regarding how horses should be managed on the land, there is also common ground as to the goal of sustaining healthy equid populations managed on healthy rangeland. In light of the charge to our committee and in the course of our public engagement, it is clear that the status quo of continually removing free-ranging horses and then maintaining them in long-term holding facilities, with no foreseeable end in sight, is both economically unsustainable and discordant with public expectations. It is equally evident that the consequences of simply letting horse populations, which increase at a mean annual rate approaching 20 percent, expand to the level of “self-limitation”—bringing suffering and death due to disease, dehydration, and starvation accompanied by degradation of the land—are also unacceptable. Those facts define the point from which we must begin the journey. However, it also provides a direction for the next steps: how can the natality be effectively managed so as to ensure that genetically viable, physically and behaviorally healthy equid populations are maintained on the land while preserving the ecosystem itself?
The committee has endeavored to examine the full array of options to meet that goal by reviewing prior National Research Council reports on the Wild Horse and Burro Program, studying existing data and current program procedures used by the Bureau of Land Management, and inviting experts to present evidence related to equid behavior, genetics, and reproduction as well as management approaches. Importantly, the committee did not limit itself to free-ranging horses and burros in the western United States but incorporated knowledge derived from the study of equid populations as diverse as donkeys in Sicily, zebras in Africa, and horses on Assateague Island and other barrier islands of the eastern United States. In a similar vein, the committee included studies of diverse ecosystems in which multiple species overlap, such as Yellowstone and the Serengeti, and lessons learned
in resolution of environmental issues in which different sectors of the public held views that once seemed irreconcilable. The committee took seriously the public’s valuation of free-ranging horses and burros on public lands, the importance of promoting a healthy multiple-use ecosystem, and the economic consequences of simply continuing the status quo. On behalf of the committee, I want to express my appreciation to each and every person who took the time, effort, and expense of providing public comment and to those who shared their “citizen science” data with the committee.
A study of this magnitude requires a tremendous commitment from the committee members. All have sacrificed evenings, weekends, and vacations—without financial compensation—in this commitment and in their desire to bring the best possible science to bear on a challenging issue. Individually and collectively, they brought a wealth of experience and knowledge and engaged in vigorous intellectual debate to meet the challenge. On behalf of the committee, I express our thanks and appreciation to the study director, Kara Laney; to Robin Schoen, director of the Board on Agriculture and Natural Resources; to Janet Mulligan, senior program associate for research; and to Kati Reimer, senior program assistant. Without their planning, organization, and editing expertise, this report would not have been possible. I also want to recognize the valuable contributions of Dr. Irwin Liu, who provided expertise on equid fertility.
Science alone, even the best science, cannot resolve the divergent viewpoints on how best to manage free-ranging horses and burros on public lands. Evidence-based science can, however, center debate about management options on the basis of confidence in the data, predictable outcomes of specific options, and understanding of both what is known and where uncertainty remains. I am confident that this study provides a centerpoint and hope that it will serve as a guide for the first step in the journey toward ensuring that genetically viable, physically and behaviorally healthy equid populations can be maintained while preserving a thriving, balanced ecosystem on public lands.
Guy Hughes Palmer
Chair, Committee to Review the Bureau of Land Management Wild Horse and Burro Management Program
This report is the product of the cooperation and contribution of many people. The members of the committee thank all the speakers who provided briefings to the committee (Appendix C contains a list of presentations to the committee). Members also wish to express gratitude to Dr. Irwin Liu, University of California, Davis, for his time and input.
This report has been reviewed in draft form by persons chosen for their diverse perspectives and technical expertise in accordance with procedures approved by the National Research Council’s Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its published report as sound as possible and to ensure that the report meets institutional standards of objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following for their review of this report:
Barry Ball, Gluck Equine Research Center, University of Kentucky
David Berman, Ozecological Pty. Ltd.
Elissa Z. Cameron, University of Tasmania
C. Rex Cleary, Bureau of Land Management (retired)
Leonard Jolley, U.S. Department of Agriculture, Natural Resources Conservation Service (retired)
Robin C. Lohnes, American Horse Protection Association
Robin K. McGuire, Lettis Consultants International, Inc.
John McLain, Resource Concepts Inc.
Colleen O’Brien, Australian Brumby Alliance
Greg Olsen, GHO Ventures, LLC
Oliver A. Ryder, San Diego Zoo Institute for Conservation Research
Donald B. Siniff, University of Minnesota (Emeritus)
Thomas Webler, Social and Environmental Research Institute
Gary C. White, Colorado State University (Emeritus)
Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations, nor did they see the final draft of the report before its release. The review of this report was overseen by coordinator, Dr. Stephen W. Barthold, University of California, Davis, appointed by the Division on Earth and Life Studies, and monitor, Dr. May R. Berenbaum, University of Illinois, Urbana-Champaign, appointed by the National Research Council’s Report Review Committee. The coordinator and monitor were responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring committee and the institution.
1 FREE-RANGING HORSES AND BURROS IN THE WESTERN UNITED STATES
Status of Free-Ranging Horses and Burros Under Bureau of Land Management Jurisdiction
2 ESTIMATING POPULATION SIZE AND GROWTH RATES
Estimating the Size of Free-Ranging Equid Populations
Density-Independent Population Controls
Consequences and Indicators of Self-Limitation
4 METHODS AND EFFECTS OF FERTILITY MANAGEMENT
Equine Social Behavior and Social Structure
Reproduction in Domestic Horses and Donkeys
Potential Methods of Fertility Control in Free-Ranging Horses and Burros
Adjustment of Sex Ratio to Limit Reproductive Rates
Female-Directed Methods of Fertility Control
Male-Directed Methods of Fertility Control
Additional Factors in Evaluating Methods of Fertility Control
Identifying the Most Promising Fertility-Control Methods
5 GENETIC DIVERSITY IN FREE-RANGING HORSE AND BURRO POPULATIONS
The Concept and Components of Genetic Diversity
Research on Genetic Diversity in Free-Ranging Populations Since 1980
The Relevance of Genetic Diversity to Long-Term Population Health
Is There an Optimal Level of Genetic Diversity in a Managed Herd or Population?
Management Actions to Achieve Optimal Genetic Diversity
6 POPULATION MODELS AND EVALUATION OF MODELS
Population Models Applied to Horses and Burros
Population-Modeling Framework Used by the Bureau of Land Management
The Wild Horse Management System Model
Alternative Modeling Approaches
7 ESTABLISHING AND ADJUSTING APPROPRIATE MANAGEMENT LEVELS
The History of Appropriate Management Levels
Evaluation of the Handbook Approach
Establishing and Validating Appropriate Management Levels: Science and Perceptions
8 SOCIAL CONSIDERATIONS IN MANAGING FREE-RANGING HORSES AND BURROS
Disparate Values Related to Free-Ranging Horses and Burros
The Case for Public Participation
Opportunities for the Bureau of Land Management to Engage the Public
The Problem with “Business as Usual”
B Previous National Research Council Reports on Free-Ranging Horses and Burros
C Presentations to the Committee
D Questions and Requests from the Committee