Photo taken at the Pryor Mountains Wild Horse Range by Meg Frederick.
The Bureau of Land Management is seeking comments on a proposed amendment to the Billings Field Office Resource Management Plan regarding genetic diversity in the Pryor Mountains Wild Horse Range.
Public comments are due by April 29.
The 2015 Resource Management Plan for the Pryor horses failed to adequately describe “all representations in the herd” in the management decision. The Resource Management Plan stated, “MD WH-7: Herd Characteristics: Within an HMAP, herd structure will be managed for all representations in the herd, not allowing specific colors or bloodlines to dominate from management manipulation.”
BLM interpreted this to mean that each mare would have an opportunity to have at least one offspring, and that objective was included in the 2009 Herd Management Area Plan (HMAP).
Plaintiffs disagreed with this interpretation and requested a temporary restraining order on a 2018 proposed gather. The court found that “BLM did not discuss the loss of patrilineal lines and established a one progeny rule without further discussion, suggesting to the court that BLM may have acted arbitrarily and capriciously by failing to consider the ramifications of the loss of horses it chose to remove.”
The proposed amendment is meant to address the risks associated with inbreeding, including the use of genetic information to determine management actions.
The BLM is suggesting the following amendment to management decision WH-7:
Maintain desirable levels of genetic diversity, as measured by Observed Heterozygosity (Ho). Observed heterozygosity is a measure of how much diversity is found, on average, within individual animals in the HMA. If Ho drops below thresholds identified in the BLM Wild Horse and Burro Handbook H-4700-1, then BLM would take one or any combination of the following actions to reduce the possible risks associated with inbreeding depression: 1) maximize the number of fertile, breeding age wild horses (6-10 years) within the herd; 2) adjust the sex ratio in favor of males (but with not more than approximately 60 percent males); or 3) introduce mares or stallions from other wild horse HMAs. Prioritize introductions from herds with characteristics similar to the Pryor Mountain horses, such as the Sulfur herd in Utah, the Cerbat Mountain herd in Arizona, or others.
Submitting a public comment
More information, relevant documents, instructions, and a venue for submitting comments are available on the BLM e-Planning project website at https://eplanning.blm.gov. Search using the NEPA number: DOI-BLM-MT-C010-2020-004-EA.