of their lives. At the time the committee’s report was prepared, long-term holding costs consumed about half the Wild Horse and Burro Program’s budget.

BLM is subject to ardent criticism from various stakeholders regarding its approach to management of free-ranging equids. Some parties express concern that the health of the range and the condition of other species that inhabit the land are adversely affected by populations of horses and burros that often exceed AMLs. Other members of the public think that horses and burros are unfairly restricted and are concerned that AMLs are too low to maintain genetically healthy herds and that horses and burros are confined to too little public land. They are also concerned about the stress placed on animals during gathers and in holding facilities.

To improve the sustainability and public acceptance of the program, BLM asked the National Research Council Committee to Review the Bureau of Land Management Wild Horse and Burro Management Program to build on previous Research Council reports on

BOX S-1
Statement of Task

At the request of the Bureau of Land Management (BLM), the National Research Council (NRC) will conduct an independent, technical evaluation of the science, methodology, and technical decision-making approaches of the Wild Horse and Burro Management Program. In evaluating the program, the study will build on findings of three prior reports prepared by the NRC in 1980, 1982, and 1991 and summarize additional, relevant research completed since the three earlier reports were prepared. Relying on information about the program provided by BLM and on field data collected by BLM and others, the analysis will address the following key scientific challenges and questions:

  1. Estimates of the wild horse and burro populations: Given available information and methods, how accurately can wild horse and burro populations on BLM land designated for wild horse and burro use be estimated? What are the most accurate methods to estimate wild horse and burro herd numbers and what is the margin of error in those methods? Are there better techniques than BLM currently uses to estimate population numbers? For example, could genetics or remote sensing using unmanned aircraft be used to estimate wild horse and burro population size and distribution?
  2. Population modeling: Evaluate the strengths and limitations of models for predicting impacts on wild horse populations given various stochastic factors and management alternatives. What types of decisions are most appropriately supported using the WinEquus model? Are there additional models BLM should consider for future uses?
  3. Genetic diversity in wild horse and burro herds: What does information available on wild horse and burro herds’ genetic diversity indicate about long-term herd health, from a biological and genetic perspective? Is there an optimal level of genetic diversity within a herd to manage for? What management actions can be undertaken to achieve an optimal level of genetic diversity if it is too low?
  4. Annual rates of wild horse and burro population growth: Evaluate estimates of the annual rates of increase in wild horse and burro herds, including factors affecting the accuracy of and uncertainty related to the estimates. Is there compensatory reproduction as a result of population-size control (e.g., fertility control or removal from herd management areas)? Would wild horse and burro populations self-limit if they were not controlled, and if so, what indicators (rangeland condition, animal condition, health, etc.) would be present at the point of self-limitation?


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