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Summer 2013 Vol. 13 Number 1

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Icons of the American West

Wild Horse roundup, photo courtesy Bureau of Land Management/Rock Springs Field Office, Wyoming

Report Offers Science-Based Strategies
for Managing Wild Horses and Burros

W ild horses are synonymous with the spirit of the American West. Just mentioning them conjures images of these animals running across the open range with their manes blowing in the wind. Although these images are iconic, the reality is that more wild horses may end up in long-term holding facilities than roaming western lands.

Federal protection and management of wild horses on western public lands began with the Wild Free-Roaming Horses and Burros Act of 1971. But now, decades later, the program is in crisis. In order to sustain healthy horse and burro populations at appropriate levels and maintain ecological balance on public lands, the U.S. Bureau of Land Management removes horses from the range and tries to place them in private homes through adoption. The challenge is that the number of animals rounded up now greatly exceeds the adoption demand, and costs for holding and caring for unadopted animals consumes about half the budget for BLM's Wild Horse and Burro Program, which aims to protect, manage, and control wild horses and burros to ensure healthy herds on flourishing rangelands. The current practice of periodically Burros for adoption, photo courtesy Bureau of Land Managementremoving a portion of the animals and keeping them in holding facilities is economically unsustainable and doesn't meet public expectations.

In addition, the animals on the range are increasing at a rate of 15 percent to 20 percent a year, meaning these populations will double in four years and triple in six years. Faced with these constraints, BLM asked the National Research Council to examine the scientific basis of its management practices. The report outlines the tools that exist for BLM to better manage the animals on healthy lands, enhance public engagement and confidence, and make the program more financially sustainable.

BLM's current removal strategy enables the high population growth rate by maintaining the number of animals below the capacity of the land, found the committee that wrote the report. But if removals were eliminated, land degradation would likely occur, leading to inadequate food and water supplies and higher death rates. Periodic droughts may cause sudden and unpredicted impacts as well. Allowing these impacts on either the horse population or the land goes against the program's mission.

"Continuing to remove the horses and placing them in holding facilities is not a long-term solution and will only become more expensive," said committee chair Guy Palmer. "BLM should explore other ways to slow the growth rate so the number of horses removed is in line with the number of animals adopted."

To help control the horse population, the committee recommended widespread and consistent application of fertility control. Three methods in particular -- porcine zone pellucida (PZP) and GonaConTM for mares and chemical vasectomy for stallions -- were identified as effective approaches.

"These fertility methods are recommended based on their efficacy with other horse populations, notably those on Assateague Island," Palmer said. "Nevertheless, scaling up use of these approaches to the larger and more dispersed horse populations in the western U.S. will be challenging."

The report also says that BLM's population surveys likely miss 10 percent to 50 percent of the animals. The committee recommended that BLM improve and standardize its methodology to estimate population size, stressing the importance of accurate counts as the basis for all management strategies.

BLM should also examine the genetics and health of the horses as well as the rangelands they occupy to assure that both the animal populations and ecosystem are appropriately managed. Moreover, developing an iterative process whereby members of the public could engage with BLM scientists on data gathering and assessment would increase the transparency, quality, and acceptance of BLM's process, concluded the committee. -- Jennifer Walsh & Lorin Hancock

Using Science to Improve the BLM Wild Horse and Burro Program: 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 (2013, 630 pp.; ISBN 978-0-309-26494-5; available from the National Academies Press, tel. 1-800-624-6242; $74.00 plus $5.00 shipping for single copies).

The study was chaired by Guy Palmer, regent professor of pathology and infectious diseases, the Jan and Jack Creighton Endowed Chair in Global Health, and director of the Paul G. Allen School for Global Animal Health, Washington State University, Pullman. The study was sponsored by the U.S. Bureau of Land Management.

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Copyright 2013 by the National Academy of Sciences