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CHAPTER l INTRODUCTION THE COMMITTEE'S CHARGE This report is submitted in partial compliance with the Public Rangelands Improvement Act of l978 (PL 95-5l4), which directs in Section l4 (b)(3) that: For the purpose of furthering knowledge of wild horse and burro population dynamics and their interrelationship with wildlife, forage and water resources, and assisting him in making his determination as to what constitutes excess animals, the Secretary shall contract for a research study of such animals with such individuals independent of Federal and State government as may be recommended by the National Academy of Sciences. The terms and outlines of such research study shall be determined by a research design panel to be appointed by the President of the National Academy of Sciences. The first step in carrying out these provisions was the creation of a contract in May l979 between the Bureau of Land Management (BLM) and the National Academy of Sciences (HAS). The contract charged the Academy with the responsibility to develop a research program that would: A. Develop data on the biology of wild horses and burros, including the population dynamics of wild horse and burro herds; B. Identify principles and procedures for managing populations of wild horses and burros in accordance with the policies and objectives of this Act; C. Develop information concerning the availability and use of forage and water resources, dietary and habitat overlaps, and other factors relevant to the determination of the number of wild freeroaming horses and burros that a herd area can sustain; and l3
l4 D. Provide the Secretaries of Interior and Agriculture with scientific information upon which to make the determination as to excess animals required by this Act. Both the Act and the contract direct NAS to impanel a committee to assess the state of knowledge relevant to the management of wild and free-roaming horses and burros, to design a research program that will provide information now lacking but essential to guide sound management, to review and oversee the 2-year research effort, and then to prepare a final report summarizing knowledge relevant to a sound management program for wild and free-roaming horses and burros. The NAS Committee on Wild and Free-roaming Horses and Burros (WFRHB) was impaneled in June l979. Phase I of the total undertaking involved the initial state-of-knowledge assessment and research design. The present document is the final report for Phase I. The state-of-knowledge assessment is a compilation of information in four general categories: (l) eguid biology, (2) the effects of equids on various ecosystem components, (3) socioeconomic aspects of the subject, and (4) research and management methodology. The research program consists of l8 projects designed to enhance knowledge in these four subject areas. While the report discusses information in terms of its relevance and adequacy with regard to various policy questions, the Committee has taken an analytical approach without advocating policy on any issues. PL 95-5l4 makes it clear that the role of the Committee and the research it recommends is to provide information to help the Secretaries of Interior and Agriculture arrive at management decisions. The Committee is now moving into Phase II by offering its services, as needed, to the BLM and the Forest Service (USFS) in the contracting procedures needed to bring the research program into operation. Once contracts are let and the research is under way, the Committee will assume its advisory responsibility on the research. SUBDIVISION AND TIMING OF THE TASK The BLM/NAS contract specifies the areas of knowledge considered important to the development of a sound horse-and-burro management program. Consideration of these areas was also vital in preparing the state-of-knowledge assessment and the research design. The contract identifies them as follows: a. Inventoryâpopulation estimates, techniques, indexes. b. Wild horse and burro population dynamicsâherd size, sex and age classes, reproduction rates, survival mortality for adults and foals, natural controls, and other population controls. c. Forage requirementsâcomparisons to wildlife and livestock.
l5 d. Impact of wild horses and burros on the public rangelandsâinterrelationships of wild horses and burros with other resource uses and activities, habitat, fish, wildlife, recreation, water and soil conservation, and domestic livestock grazing. e. Socio-economic relationships of population control and management. At its first meeting in Salt Lake City on June 28-29, l979, the Committee outlined subtopics encompassed by the four subject areas described in the previous section. The subtopics fell into three general categories: l. Biology of horses and burros, with primary attention to demography, behavior, genetics, nutrition, and physiology, and to environmental influences, both physical and biotic, that affect these equids. 2. Effects of horses and burros on various components of the ecosystems of which they are a part, especially vegetation, domestic animals, wildlife, and watersheds. 3. Legal, economic, and sociopolitical issues surrounding horse and burro management. These three categories were assigned as the purview of the three following subcommittees, respectively: Subcommittee l: Walter Conley (Chairman), Francisco Ayala, Lee Eberhardt, Patricia Moehlman, and Ulysses Seal; Subcommittee 2: John Malechek (Chairman), John Artz, Wilbert Blackburn, Gerald Gifford, J.W. Swan, and Frederic H. Wagner (Gifford served on the Committee from September to December l979, and when he resigned, Blackburn took his place); Subcommittee 3: Walter Johnston (Chairman), Gail Achterman, Sally Fairfax (NAS Board on Agriculture and Renewable Resources Liaison to the Committee), and Stephen Kellert. Each subcommittee then set about the task of gathering state-of-knowledge information from a variety of sources and designing the needed research. The entire Committee met five times: June 28-29, l979 at Salt Lake City, Utah July 6-7, l979 (including a l-day public hearing) at Reno, Nevada September 6-8, l979 (including attendance at A Symposium: The Ecology and Behavior of Feral Equids, conducted at Laramie, Wyoming) October 27-28, l979 at Las Cruces, New Mexico January 26-27, l980 at Davis, California
16 In addition, several subcommittee or partial subcommittee meetings were held at various sites. On December 6, l979, the Committee Chairman and representatives of Subcommittees l and 2 met with BLM and USES officials in Logan, Utah to begin developing requests for proposals (RFPs) on census research and on projects to study equid habitat selection, food preferences and consumption rates, vegetation and watershed impacts, and blood assays as nutritional indices. On April 7, the Chairman and two other Committee members met with BLM and USFS officials in Denver to review proposals generated by the RFPs. The Phase I tasks were to be completed by October 3l, l979. In July, the Committee requested an extension of the due date specified in the contract. It proposed to submit an interim state-of-knowledge assessment on October 3l along with the design of that portion of the research that must span two horse-breeding seasons, and a completed Phase I report on December 3l, l979. NAS granted the extension. The interim report was duly submitted and has been reproduced and distributed by NAS. By December l979, it was clear that still more time was needed to prepare the final report, and another extension was requested and granted. As noted above, this report is the culmination of Phase I. STRUCTURE AND BASIS OF THE REPORT The report consists of four major chapters and three appendixes. Following this introductory discussion, Chapters 2, 3, and 4 describe essentially the subject matter of the three subcommittees. Chapter 5, on research and management methodology, is a joint effort of Subcommittees l and 2. Appendix A is a lengthy review of equine cecal digestion; Appendixes B and C are annotated bibliographies on grazing hydrology and economic and sociopolitical issues, respectively. Each of *he four major chapters is divided into two parts. The first is a state-of-knowledge assessment. The second is a description of research projects that are needed both to fill gaps in knowledge revealed by the state-of-knowledge assessment and to provide a data base for a sound management program. The state-of-knowledge assessment surveyed the published literature thoroughly. Mimeographed material, intradepartmental and other unpublished reports, as well as theses and dissertations were reviewed, but less completely. The great store of unanalyzed, unpublished data in the files of agencies, organizations, and individual observers was consulted to some degree, but the Committee thus far has not had enough time to make thorough or far-reaching analyses and interpretations of them. Still another considerable store of knowledge lies in the unrecorded experience of hundreds of range managers, wildlife ecologists, and lay devotees of horses and burros. This source has hardly been tapped by the Committee, again because of time limitations. It is the scientist's responsibility to gather and weigh evidence, regardless of its source, and to asses both its quality and the manner in which it was procured. The current review could not avoid a heavy concentration on the published literature and a less thorough
l7 treatment of raw data and information based on experience. Published literature tends to lag behind the accumulated store of knowledge, and heavy reliance upon publications may produce inadequate or biased understanding. The state of the art will not be fully assessed until the Committee has an opportunity to go afield with range managers, wildlife biologists, and amateur horse and burro observers. The members began to do this in the summer of l980, but until that work is completed, the Committee must continue to rely heavily on the published literature. The l8 recommended research projects are listed below in an order that deviates somewhat from that in the interim report. l. Habitat Preference and Use by Co-occurring and Separately Occurring Feral Equids and Cattle 2. Food Consumption Rates and Nutrition of Wild and Free-Roaming Horses and Burros and Their Associated Species 3. Nutritional Plane, Condition Measures, and Reproductive Performance in Domestic Mares 4. Blood Assay of Experimental Equids and Livestock in Projects l, 2, 3, 5, and 8 5. Demography of Wild Horses and Burros 6. Social Structure, Feeding Ecology, and Population Dynamics of Wild and Free-Roaming Horses and Burros 7. Genetic Polymorphism 8. Grazing Impacts of Equids and Cattle on Range-Plant Communities 9. Hydrologic Impacts l0. Riparian-Zone Impacts ll. Public Attitudes l2. Analysis and Evaluation of Demands for Excess WFRHB l3. Management Costs of WFRHB Alternatives l4. Economic Considerations for Management Alternatives Drawn from Proposed Research Programs l5. Nonmarket Values for WFRHB l6. Conceptual Development of Public Rangeland Management Models
l8 l7. Census Methods for Wild Horses and Burros l8. Contraception Studies The projects are discussed more fully in the following chapters of this report.
