Rock & Hank from the Castle Rock Herd

Rock and Hank, our younger breeding bulls, came to us from Ted Turner Enterprises Castle Rock Conservation Herd at the Vermejo Park Ranch in Northern New Mexico in February 2023.

The animals of the Castle Rock bison herd were transplanted to Vermejo Park Ranch along with elk from Yellowstone National Park sometime between 1920 and 1940. In the 1950's, thirteen bison from Philmont Scout Ranch were released with the Castle Rock bison. The Philmont herd was originally founded from bison purchased from Yellowstone in the early 1920's. In the 1980's, 6 bulls from the foundational Maxwell herd in Kansas were introduced to the herd. Since that time, the Castle Rock herd has been closed. Over many generations without human intervention, the Castle Rock bison became well-adapted to their high-elevation, mountain and canyon environment, thriving through periods of variable precipitation and forage production.

Texas A&M University performed a Conservation Genetic Analysis of the Castle Rock Bison (Derr and Marshall, 2010) using 14 nuclear microsatellite markers and mitochondrial DNA genotyping and found that the overall level of possible introgression in the was below the detection limit of current technology.

Contemporary genetic technologies were also used to determine the level, distribution, and origin of genetic diversity in the Castle Rock herd. The study concluded the Castle Rock herd retains many of the unique alleles present in Yellowstone National Park bison, sharing 99 alleles with Yellowstone bison, while also maintaining 16 unique alleles. In addition, the Castle Rock herd also clusters genetically with Wichita Mountains National Wildlife Refuge (OK), Wind Cave National Park (SD), Fort Niobrara National Wildlife Refuge (NE), and the National Bison Range (MT).

The Castle Rock bison have been proven unique both historically and genetically. These animals hold a large portion of the genes (they have genes from 4 of the 6 foundation herds) that originated from North American bison before European settlement of the West (pre-1850), making them one of the few privately held "foundation genetic" herds.