BLM Proposes Changes to Manage Pryor Mountains Wild Horse Herd for Genetic Diversity
- The Bureau of Land Management (BLM) has opened a protest period regarding its proposal for managing the Pryor Mountains wild horse herd.
- To monitor genetic diversity, the BLM will employ a measure called observed heterozygosity.
- The BLM's proposal revises past management practices that were called “ambiguous” and “mathematically impossible.” The previous approach sought to preserve all color and bloodline representations without allowing any...
BLM Proposes Changes to Pryor Mountains Wild Horse Management
The Bureau of Land Management (BLM) has opened a protest period regarding its proposal for managing the Pryor Mountains wild horse herd. The plan aims to achieve "desirable levels of genetic diversity" in the herd, which currently consists of about 200 horses—116 females and 84 males.
To monitor genetic diversity, the BLM will employ a measure called observed heterozygosity. This statistic reflects the average diversity within individual animals. The Pryor herd, known for its connection to Ginger Kathrens’ documentaries featuring the stallion Cloud, inhabits a high desert region along the Montana-Wyoming border.
The BLM’s proposal revises past management practices that were called “ambiguous” and “mathematically impossible.” The previous approach sought to preserve all color and bloodline representations without allowing any specific traits to dominate. Critics, including the Cloud Foundation and the Pryor Mountain Wild Mustang Center, have raised concerns about the potential negative impact of the BLM’s plans on the herd’s unique genetic traits.
The BLM’s 2013 genetic analysis indicated that the Pryor herd has strong Spanish ancestry. However, a study published in 2024 suggests that the herd’s genetics are similar to those of numerous other BLM-managed wild horse herds. Consequently, the BLM sees the Pryor herd not as an isolated population but as part of a larger group of wild horses.
To maintain overall herd health, the BLM is proposing to reduce the population by 50 horses over the next two years based on updated criteria. This decision has sparked significant public feedback; among 3,000 comments, many advocated maintaining a population of between 150 and 200 horses to sustain genetic diversity.
Experts from the U.S. Geological Survey assisted the BLM in assessing genetic impacts of population control measures. Their findings indicated that both random removals and lineage-based removals could preserve genetic diversity for the foreseeable future.
The BLM plans to continue introducing horses from similar populations to prevent inbreeding. Additionally, they will monitor the health and genetics of the herd closely.
Public protests regarding the proposed management changes can be submitted until December 16. Details are available on the BLM website.
The current management goal emphasizes maintaining a healthy balance in the 39,994-acre horse range. Officials have noted that overpopulation is negatively affecting the health of the land and its wildlife, including bighorn sheep.
The BLM plans to employ baited traps to capture and remove the targeted horses. After a long pause in removals, the last round of removals took place in 2015. The agency aims to lower the population to between 107 and 120 adults, excluding foals. Despite past removals, every horse has been successfully adopted due to the herd’s popularity.
The business of horse management continues, with public engagement and animal welfare at the forefront of discussions.