Left unchecked, wild horse and burro numbers can increase by 20% or more each year. Wildlife populations are kept in check through hunting and natural predators. Livestock use is controlled through limits outlined in the grazing permits issued to ranchers. Because horses and burros are an introduced species, they have few natural enemies and are protected from hunting, illegal capture or harassment under federal law. In the absence of these controls, there is a danger that wild horse and burro numbers will grow to the point the land can’t support them.
Each year, BLM Nevada gathers hundreds wild horses and burros to protect land health. The excess animals are transported to BLM holding facilities where they are prepared for adoption through the Adopt-A-Horse (or Burro) Program.
Many of Nevada’s wild horses and burros are captured using helicopters and motorized vehicles. BLM may also use bait or water trapping or remove animals from horseback, if appropriate. These methods are generally used to remove smaller numbers of animals in locations with good road access. However, helicopter assisted gather operations have proven to be more humane, effective and efficient when larger numbers of animals require removal over large acreages or rugged terrain. In these situations, the helicopter is better able to move the horses around barriers such as fences or roads at a pace which assures the animals arrive at the trap in good condition. Helicopters are able to move horses and burros at a pace that allows mares and foals to stay together. Once they enter the trap (corral), they are transported to a temporary holding facility where they are sorted by age and sex and fed hay and water. BLM personnel are on-site throughout the gather operation to assure humane treatment of the captured animals.
Nevada is also continuing to participate in BLM’s fertility control research. Fertility control has been implemented on nearly 30 Nevada HMAs. However, fertility control is not 100% effective. Nor, do predation or disease effectively slow wild horse population growth. In the absence of an effective and affordable means of fertility control, capturing and removing excess animals from the range is needed to protect rangeland condition and herd health.
An effective fertility control agent has not yet been perfected for use in wild horses. BLM is continuing research aimed at finding an effective and longer-lasting fertility control agent. Nevada is continuing to participate in this research and has applied fertility control to over 1,200 mares in nearly 30 HMAs (2005-2008).
|Did You Know? |
A population of 300 horses can double in four years to 600 animals -- that can severely impact desert rangelands with scattered, small water sources like we have in Nevada.
Frequently Asked Questions (FAQs)
Q – What provides BLM with the authority to use helicopters and motorized vehicles in managing Nevada’s horses and burros?
A – Congress amended the WFRHBA in 1976 to provide BLM with the authority to use helicopters to inventory and assist in capturing animals and the use of motorized vehicles to transport captured animals. The law also requires that a public hearing be held prior to the use of helicopters and motorized vehicles. Hearings are held in Nevada annually.
Q – Is using helicopters and motorized vehicles safe and humane for the animals?
A – Yes. Prior to the passage of the 1971 WFRHBA, mustangers used fixed wing aircraft and motorized vehicles to roundup wild horses and burros with none of the controls we have today. Since the passage of the 1971 Act, all capture and handling activities are conducted in accordance with established Standard Operating Procedures (SOPs). BLM personnel are on site throughout the capture operation to assure humane treatment of the animals. From time to time, BLM Nevada also invites representatives from humane groups and the media to observe wild horse and burro gather operations.
The use of helicopters and motorized vehicles has proven to be a humane, effective and practical means for the gather and removal of excess wild horses and burros from the range. This is demonstrated by the capture of nearly 23,000 excess animals during 2004-2008 in Nevada with a mortality rate of one-half of one percent (.005%) which is very low when handling wild animals.
Q – What are some of the impacts that can result from gather and transportation of captured animals?
A – Impacts to individual animals such as nervous agitation and physical stress can result. Indirect impacts can also occur including biting, kicking, bruises or other injuries. Mortality from this impact is infrequent but does occur in about one-half to one percent of wild horses captured in any given gather. The risk for spontaneous abortions in mares is rare.
Q – What qualifications do gather contractors have? If they treat an animal inhumanely, does BLM take action?
A – Prior to being awarded a gather contract, potential contractors undergo a rigorous technical program review by a team of experts. Potential contractors must meet all the terms and conditions required in the Bureau’s application process and tangibly demonstrate they have the knowledge, skill, ability, expertise, labor and equipment needed to humanely capture, handle and transport wild horses and burros.
BLM takes reports of misconduct by gather contractors very seriously. Such reports are investigated and BLM will take appropriate action, up to and including cancelling the gather contract depending on the severity of the misconduct.
Q – Why doesn’t BLM use bait or water trapping or capture the animals from horseback?
A – BLM does use these methods when appropriate. They are generally most effective when smaller numbers of animals need to be removed in locations with good road access.
Q – Why doesn’t BLM apply fertility control or allow predators to control populations rather than continue to remove excess animals from the range?
A – An effective fertility control agent has not yet been perfected for use in wild horses. BLM is continuing research aimed at finding an effective and longer-lasting fertility control agent. Nevada is continuing to participate in this research and has applied fertility control to over 1,300 mares in nearly 30 HMAs (2005-2008).
Nor, do predation or disease effectively slow wild horse population growth. Predators such as mountain lions and bobcats are generally not present in large enough numbers to effectively control populations. Because wild horses and burros have effectively adapted to the rigors of the Nevada environment, few diseases affect them.
In the absence of an effective and affordable means of birth control, capturing and removing excess animals from the range is needed to protect rangeland condition and herd health.
Q – What has BLM done to find an effective fertility control agent?
A – BLM has supported the development of an effective contraceptive agent for wild horses since 1978. The goal for an effective fertility control program is to slow the annual growth rate in wild horse populations in order to extend the time between gathers and to decrease the number of excess animals which need to be removed. The most promising agent is PZP vaccine. However, it is not commercially available. BLM is using the vaccine under an investigational exemption issued by the Food and Drug Administration (FDA) and held by the Humane Society of the United States (HSUS).
The most effective formulation is a one year vaccine that must be administered annually (about 90% effective if administered during November-February). However, it is not feasible to gather wild horse herds every year to administer the vaccine and it is very difficult to approach most wild horses on western rangelands close enough to allow for remote delivery (darting). A second set of field trials is evaluating the effects of a longer lasting, approximately 2 year agent (the 2 year agent is about 70-90% effective depending on time of application), on population growth while monitoring the safety of the product. To achieve maximum effectiveness, mares must be treated during a 3-4 month window prior to foaling.
In order to significantly reduce herd growth rates and achieve meaningful cost-savings, development of a longer-acting agent is needed. As a result, BLM has funded an additional 5 year research project to develop a single injection, 3-4 year fertility control vaccine. These experiments include laboratory development and testing in wild horses held in captivity. Initial tests in captive wild horses identified a problem with the manufacturing process, but the laboratory work continues and is expected to produce a safe and more effective fertility control agent at some point in the future.
Q – Why doesn’t BLM geld (sterilize) the stallions then turn them back out?
A – BLM generally captures only about 80-85% of the animals present during any given gather, leaving 15-20% of the animals uncaptured. Of these, about half of the uncaptured animals are stallions which would remain available to breed the mares.
The application of fertility control to stallions as a means of population control has been the subject of debate for several years. Anecdotal reports from the field (Coates-Markle, personal communication 2003) suggest that 15-40% of foals in a band may be sired by a stallion other than the dominant harem stallion. This is supported by scientific literature that reports 15-30% of foals were not sired by a stallion associated with the dam’s band (Bowling 1990, Kaseda 1996). The stallion approach, as a means of contraception, has been studied in a small number of stallions in a limited number of herds. Kirkpatrick (1982) studied the effect of a short acting agent (testosterone proprionate, lasts 3-6 months) used in bands with only one stallion and reported that foaling was reduced by about 80%. However, Eagle (1993, also reported by Asa 1999) studied the effects of surgical vasectomy in 2 more diverse Great Basin Herds and did not find as promising a result. Foaling rates only seemed lower in one HMA in the first year of the study, with only a marginal effect reported for the second year and no significant affect detected in 6 of 7 observations over two years in a second HMA. The authors concluded that “although sterilization of dominant males may be an effective treatment to reduce foaling in a small sample of bands selected from a population, this treatment might not limit population growth.”
Q – Why doesn’t BLM consider other fertility control agents such as SpayVac or Gonacon?
A – GonaCon™ is an experimental fertility control vaccine. Presently, applications of GnRH are being researched in controlled field studies for potential use as a wildlife management tool for deer. Tests of the GnRH vaccine are ongoing in several states and countries, involving a wide range of wildlife and feral species, including horses. At present, the effectiveness of GonaCon™ as a fertility control agent appears similar to or less than PZP-22 which BLM is currently using, suggesting limited potential for development of an effective longer-lasting fertility control agent.
SpayVac™ is an experimental fertility control vaccine using PZPantigens. A single vaccination with SpayVac™ has maintained a high level of contraception throughout the 4-year Nevada estray horse study. There is no regulatory approval for the management or investigational use of SpayVac™ through EPA or FDA. There is no SpayVac™ available for investigational use and no one is currently making it. Data is not available that describes the impact of SpayVac™ on the behavior and physical health of the mares. SpayVac™ may have potential for use as an effective, longer-lasting fertility control agent in the future. It may also offer an alternative to spaying mares in the future. However, additional research over the next 5-10 years would be needed before it could be used on a population-management basis.
Q – Why doesn’t BLM capture the herds and treat them with PZP every two years, rather than gathering and removing large numbers of horses every year?
A – BLM is currently taking a strategic look at a number of options to slow the population growth of WH&B herds in Nevada and reduce the number of WH&B which must be removed to achieve and maintain AML. Several possible management options are currently being considered, including the option to capture and treat herds with PZP every two years. In exploring and evaluating the possible options, BLM is working closely with field office WH&B specialists as well as representatives from the three Nevada Resource Advisory Councils (citizen advisory groups).
Q – How does BLM determine if excess animals are present?
A – BLM monitors grazing utilization, trend in range condition, actual use, population data, and other factors to determine if excess animals are present and removal is necessary to restore the range to a thriving natural ecological balance and prevent a deterioration of the range.
Q – What authority does BLM have to remove excess animals from public rangelands?
A – Section 3 (b) (2) of the 1971 Wild Free-Roaming Horses and Burros Act (WFRHBA) provides BLM with that authority to remove wild horses and burros from the range. This statute requires BLM to remove excess animals from the range when overpopulation exists and removal is necessary to restore a thriving natural ecological balance and to protect the range from the deterioration associated with overpopulation of horses and burros.
Q – Are BLM decisions to remove excess wild horses or burros subject to public review?
A – Yes. Gather Plan environmental assessments are made available to the public for a thirty day review and comment period unless there is an emergency situation which threatens the animal’s survival. Any person adversely affected by a decision to remove excess animals may also file an appeal of that decision.
Q – Why can’t BLM haul water or feed to the animals instead of removing them?
A – The 1971 WFRHBA requires BLM to manage horses and burros as wildland species and not as livestock. The agency does not typically haul feed or water to the animals, but does intervene in cases of extreme drought, fire or freezing weather. In managing the animals, BLM uses the minimum feasible level of management necessary to achieve healthy populations of horses and burros in balance with other uses and the land’s capability.
This direction is consistent with Congress’ intent in passing the 1971 WFRHBA (refer to Senate Conference Report 92-242) which states: “An intensive management program of…physical care would destroy the very concept this legislation seeks to preserve.” Rather, the animals should be left alone to fend for themselves.