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Conclusions and Recommendations The following four conclusions are based on the data and information available to the committee as of April 1990. 1. The genetics studies show that in any given year about one-third of the foals in bands are not sired by the dominant stallion, and a high degree of heterozygosity exists in wild horses, which originated largely from do- mestic breeds in the Oregon and Nevada study areas. 2. The Lovelock pen studies have produced steroid dosages, a delivery vehicle, and a surgical procedure that block pregnancy in at least 70 percent of treated mares for at least 28 months. The treatment does not appear to cause abortion in mares that are pregnant when it is administered. 3. The dominant-stallion vasectomy study has had ambiguous results. The data suggest a reduced foal production in the Flanigan area in the first breeding season following surgery. However, the treatment was not effective in Beaty Butte. The research team is analyzing the data in greater depth. 4. The 1988 and 1989 field observations indicate that steroid implantation in mares effectively reduces foaling rates from the 40 percent to 50 percent levels observed in untreated and placebo-implanted mares, to a level of less than 10 percent for at least 2 years in steroid-implanted mares. This research has been expensive, logistically difficult, and carried out under limiting financial and time constraints. The subjects are powerful, spirited animals that are difficult to handle and risk injury when penned or handled. To a considerable degree, the methodology has been developed anew, under difficult and risky environmental conditions. Fortunately, one helicopter crash during the course of the study did not result in any casual- ties. Sadly, there have been injuries to and losses of animals. While regret- 36
CONCLUSIONS AND RECOMMENDATIONS 37 table, the numbers lost do not invalidate the results of the research. Overall, the committee feels that the research has been conducted professionally and as effectively as possible under the prevailing constraints and conditions. The committee recommends continuing observations in the fertility con- trol studies to determine how long the implants effectively control fertility. The implanted mares now held in the Oklahoma horse reserve should be maintained and their blood sampled annually until hormone levels are not significantly different from controls. To determine the longevity and effects of implants in the field, field monitoring of steroid- and placebo-implanted mares should continue through 1990. Because of objections to helicopter use for this work, attempts should be made to obtain these data from the ground. The use of chemosterilants in herd management should be evaluated in contrast to other viable control options, and not unduly discounted because of problems that occurred during field research experiments. The loss of 48 animals at the Clan Alpine study area, collar wounds, and possible foal orphaning were products of the research procedures. These problems would not occur normally during the routine application of fertility control for herd management. The committee believes that the research to date shows some promise for controlling the wild and free-roaming horse population, and at reduced cost and need for adoption. The use of alternative methods is a decision to be made by the Bureau of Land Management (BLM). Clearly, major influences on BLM's decision will be the goals for the program and the resources provided by Congress to administer it.
