BLM seeks input on analysis of McCullough Peaks herd plan and proposed bait trap gather


July 20, 2023

The Bureau of Land Management Cody Field Office has released an environmental assessment that analyzes future wild horse bait trap gathers and fertility control measures needed in the McCullough Peaks Wild Horse Herd Management Area for the next 10 years. The public comment period is open July 13–Aug. 12, 2023.

The McCullough Peaks HMA is located east of Cody in Park County. The HMA’s appropriate management level — the point at which the wild horse population is consistent with the land’s capacity to support it and other mandated uses of those lands — is 70–140 wild horses. The current population is 181 horses, based on direct counts in 2023.

“We need to conduct small bait trap gathers and fertility control measures in the McCullough Peaks to return the population to within its AML and slow population growth, protecting the health of public land and supporting healthy horses,” said Cody Field Manager Cade Powell. BLM could begin a bait trap gather later in 2023.

According to the environmental assessment, “The BLM protects, manages, and controls wild horses and burros under the authority of the Wild Free Roaming Horses and Burros Act (WFRHBA) of 1971, as amended. The WFRHBA mandates that BLM manage wild horse populations that prevent deterioration of the rangelands and help maintain a “thriving natural ecological balance” (TNEB), while allowing multiple use within the McCullough Peaks HMA. BLM accomplishes this goal by identifying the “appropriate management level” (AML) for each herd management area. An AML is generally a population range that allows the rangelands to maintain TNEB.

“The 2015 Cody Record of Decision and Approved Resource Management Plan (2015 Cody RMP) identified the appropriate management level (AML) for McCullough Peaks HMA as a population between 70 and 140 wild horses. Since 2011, the herd within the McCullough Peaks HMA has been treated with Porcine Zona Pellucida (PZP, an immunocontraceptive used on the herd since 2011). However, population size has increased by an average of 2% per year due to several horses not responding to PZP treatments and because BLM allows mares to foal to provide genetic diversity to the herd.

“Additionally, the life expectancy is averaging 17 years with several mares currently over 20 years old. Within the McCullough Peaks HMA horses are reaching over 25 years old, five years longer than the average lifespan of a wild horse. The population size is based on direct counts completed in 2023. Projected, herd sizes for the years 2024-2034 are based on current management, which allows for a 2% growth rate per year. If BLM ceases managing wild horses through population control measures, wild horse herd population typically increase by 20% per year.”

Based on the 2% increase projection, the herd size would be at 200 by 2028 and 221 by 2033.

The proposed action based on the environmental assessment is to “conduct a bait trap gather to remove excess horses within the McCullough Peaks HMA to achieve AML. The gather would allow older horses to remain within the McCullough Peaks HMA. The BLM would continue current use of PZP, however, the proposed action would implement additional population growth suppression treatments (i.e., Gonacon, another immunocontraceptive) on mares older than 13 years old and that have contributed to the genetic diversity of the herd. In subsequent years, the BLM would maintain the population within AML through maintenance gathers if the population continues to exceed AML.”

Regarding the bait trap gather, the proposed action would have immediate trapping efforts likely conducted by BLM staff. In subsequent years a contractor may be utilized.

Per the assessment, “BLM staff familiar with the identification of the horses will help ensure that family bands will remain together, and the proper horses slated for removal are safely trapped.”

According to the assessment, “During the external scoping period, there was concern from the public that older horses within the McCullough Peaks HMA would be gathered and due to their age would immediately become sale authority horses without the possibility of adoption or end up living in a long-term care holding facility which is an enormous cost to support these horses. Therefore, the Cody Field Office will not remove the older population of horses living within the McCullough Peaks HMA.


Per the assessment regarding care of the horses once they are gathered, “Wild horses that are gathered would be transported from the gather sites to a temporary holding corral. Mares would be identified for fertility control and treated at the corrals. The horses would be provided good quality hay and water. At the temporary holding facility, a veterinarian, when present, would provide recommendations to the BLM regarding care and treatment of recently captured wild horses. Any animals affected by a chronic or incurable disease, injury, lameness or serious physical defect (such as severe tooth loss or wear, club foot, and other severe congenital abnormalities) would be humanely euthanized using methods acceptable to the American Veterinary Medical Association (AVMA).

The environmental assessment is available for review and comment on our ePlanning website (“Participate Now” in left sidebar navigation) at

You must submit all input by Aug. 12, 2023.


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