US public opinion of reproductive control options for free-roaming horses on western public lands

Free-roaming horses (Equus ferus caballus; horses) inhabit public rangelands located primarily in 10 western U.S. states. Recent horse population increases are impacting rangeland ecosystems, native wildlife species and their habitats, and exacerbating conflicts with domestic livestock grazing. While contraceptives and physical sterilization are promising options to manage horse herd levels, public opinion concerning the use of fertility control is not well understood. To better inform policymakers, we completed a rigorous study of a random sample of public land stakeholders across the United States (n = 3,500) in 2020 using a Likert scale online survey to assess their level of agreement with the general use of reproductive controls and their preferences regarding 4 available reproductive control options. We used chi-square likelihood ratio tests to determine the associations between the knowledge of horse origins in North America and horse management in the United States, and public support of contraception and sterilization methods to control horse populations. We also assessed the associations between survey responses and respondent demographics. Most respondents either "somewhat agreed" or "strongly agreed" with the use of contraceptives to control horse birth rates (36.6% and 26.9%, respectively) when no specific type of contraceptive was described. Respondents who believed horses were native to North America "strongly agreed" with the statement regarding the use of contraceptives less often (22.2%) than respondents who recognized that European explorers introduced horses (36.6%) or believed horses arrived by crossing a land bridge (35.8%); however, this association exhibited very low power to predict the response (? < 0.1). Similarly, while there were some associations indicated by chi-square analyses between demographic variables and support for contraceptives, these associations exhibited very low power to explain the responses. When asked to rank 4 generalized population control options, more respondents ranked physical sterilization as their preferred option (37.1%). There was an association between age and ranking order of sterilization. For ages 18-53, the range was 40.6-45.3%, significantly more than older ages, 54 to & GE;73, where the range was 31.1-33.8%. Knowledge did not influence the preference for control options. Our results suggest that our respondents were more supportive of the use of contraceptives or sterilization, when described in generalities, to control the birth rates in free -roaming horses. Our research provides policymakers with objective, novel insights into public knowledge and perceptions concerning the population control of free-roaming horses on designated western rangelands. We encourage the federal, state, and tribal agencies charged with the management of free-roaming horses to develop and deliver outreach programs to better educate public land stakeholders about the ecological and economic impacts of free -roaming horses on western landscapes and efficacy of available population management options to mitigate impact and sustain herds.