Issues around America’s free-roaming horses that inhabit the western rangelands tend to be presented through a “politicized lens”, a review suggests.
Solutions to reduce herd sizes faced issues of ethics and perception, according to the report published in The Professional Animal Scientist.
Lead author Lori Ward and her colleagues said the difficulty in passing feral horse legislation was summed up by the late wildlife contraceptive researcher Jay Kirkpatrick, who in 1994 observed: “The public’s view of this spectacular animal is as diverse as the ranges they inhabit.”
The Mississippi State University review team cited more than 40 papers in their examination of what they characterized as the challenges and opportunities in the rising horse population on the rangelands.
The Wild and Free-Roaming Horses and Burros Act of 1971 was established to resolve conflicting beliefs around the horses, and has been described as the driving force for educational programs associated with this management, the review team noted.
“Because most US citizens have little or no direct relationship with the feral horse problem, they are dependent on information provided by other sources such as the Bureau of Land Management (BLM) along with lobbying groups and so on, thus, creating a ‘politicized lens’ through which feral horse issues are viewed.
“Nevertheless, with the recent concern over unwanted horse numbers in the US becoming front and center in US politics, the plight of the feral horse has also become publicly acknowledged.
This, they said, had highlighted the need for education, further study, and resolution.
Horses that roam the rangelands are free-ranging descendants of once-domesticated horses. In 2015, the number of feral horses in the US western ranges was estimated at 58,150. With few natural predators, populations would continue to rise, with the potential to double every four years.
“The ever-expanding population of feral horses is a critical but not simple problem to solve,” Ward and her colleagues wrote.
“Understanding the nature of the feral horse is a crucial part of the solution process.
“Any solution to this problem must have an understanding of current populations of horses in each ecosystem, the carrying capacity of the ecosystem, and consideration of how these numbers will naturally vary.”
In the 1950s, to combat rising populations, many feral horses were slaughtered by various means, including by poisoning watering holes. This solution was met with public outrage and led to Congress passing the Wild Free Roaming Horse and Burro Act of 1971, which protected feral horses as a link to the country’s national heritage.
The act protected horses on federal land and kept them from slaughter, prompting new efforts at population control. Since that time, the BLM has paid to keep captured horses in grazing allotments, where they can be managed and adopted-out.
Many horses do not get adopted, however; likewise, the process of rounding-up feral horses is expensive and accumulated costs to maintain captive feral horses are estimated to exceed $US1 billion by 2030. Such rising costs may end the adoption practice in coming years, according to the BLM.
“At several locations, the feral horse numbers have exceeded the carrying capacity of the land on which they are living. Nevertheless, some equine experts fear that radically reducing the number of horses in the wild due to human control can cause a loss of genetic diversity. It is argued that finding the balance between a sustainable ecosystem and a population large enough for genetic diversity is a necessity.”
Excessive population density can pose an issue for vegetation health, herd health, and the indigenous population’s health, the review said.
“In the past, animals in overpopulated areas were herded into groups for removal from BLM managed areas every three to five years. Currently, managers are still working to control the herd size and manage the population through sales, adoption programs, and fertility control methods.
“However, new techniques need to be developed to estimate population size more accurately and examine the effectiveness of fertility control measures.”
They continued: “It appears more effective methods of controlling the expanding feral horse populations today are contraceptives and castrations.”
The practice was controversial, as animal welfare activists often did not agree with the use of contraceptives, but the United States Humane Society was in support of such measures.
Contraceptives, such as porcine zona pellucida vaccine, castration, or vasectomy, have not been without side effects. However, these methods may only slow growth, or in the case of vasectomy have no effect on foal rates; likewise, they may disrupt seasonal patterns within the herds among other changes.
The reviewers noted that, since 1971, 270,000 horses had been removed from public lands.
Posing the question, “Is there a solution,” the review team observed: “The feral horse population is respected for its historical significance in the exploration of North America and the US, triggering emotional responses at any discussion of controlling this population.
“Politicians have to balance these emotions with financial considerations to find a solution.
“Nevertheless, determining the most effective management practices requires knowledge of the politics of the public as well as the horse population dynamics.
“As discussed in this review, the information needed to make these management decisions is limited and often just based on estimates, requiring further study and research for reaching a more effective management solution.”
They said that while contraceptive vaccines appeared to be an acceptable solution for all groups concerned with the run-away population, there were still further questions concerning their long-term effectiveness that would need to be addressed through further investigation and study.
“In the end, the solution to the feral horse population begins with continued research.”
“Review: Challenges and opportunities in rising feral horse populations,” by J. L. Ward, S. Lindsey, J. M. Martin, M. Nicodemus, and E. Memili (doi:10.15232/pas.2015-01415) appears in The Professional Animal Scientist, volume 32, issue 6 (December 2016), published by Elsevier.
The full review can be read here.