Using Science to Improve the BLM Wild Horse and Burro Program

Using Science to Improve the BLM Wild Horse and Burro Program: A Way Forward reviews the science that underpins the Bureau of Land Management's oversight of free-ranging horses and burros on federal public lands in the western United States, concluding that constructive changes could be implemented. The Wild Horse and Burro Program has not used scientifically rigorous methods to estimate the population sizes of horses and burros, to model the effects of management actions on the animals, or to assess the availability and use of forage on rangelands.Evidence suggests that horse populations are growing by 15 to 20 percent each year, a level that is unsustainable for maintaining healthy horse populations as well as healthy ecosystems. Promising fertility-control methods are available to help limit this population growth, however. In addition, science-based methods exist for improving population estimates, predicting the effects of management practices in order to maintain genetically diverse, healthy populations, and estimating the productivity of rangelands. Greater transparency in how science-based methods are used to inform management decisions may help increase public confidence in the Wild Horse and Burro Program.Table of ContentsFront MatterSummary1 Free-Ranging Horses and Burros in the Western United States2 Estimating Population Size and Growth Rates3 Population Processes4 Methods and Effects of Fertility Management5 Genetic Diversity in Free-Ranging Horse and Burro Populations6 Population Models and Evaluation of Models7 Establishing and Adjusting Appropriate Management Levels8 Social Considerations in Managing Free-Ranging Horses and Burros9 A Way ForwardAppendix A: Biographical SketchesAppendix B: Previous National Research Council Reports onFree-Ranging Horses and BurrosAppendix C: Presentations to the CommitteeAppendix D: Questions and Requests from the CommitteeAppendix E: Herd Management AreasAppendix F: Pairwise Values of Genetic Distance (Fst)