VERMEJO PARK RANCH

Location – Raton, NM

Acquired: 1996

Size – 561,000 acres

CASTLE ROCK HERD

Cows Exposed – 625

Cow: Bull Ratio – 8:1

Maximum bull age – 5 years

Management Overview

The 561,000-acre Vermejo Park Ranch is located in northern New Mexico’s Colfax and Taos Counties, extending to the north into Colorado’s Las Animas and Costilla Counties.  The extensive property ranges across multiple ecosystems, ranging from the short-grass prairie of eastern New Mexico to the alpine tundra of the Sangre de Christo mountains.  Ranch elevations range from 6,430’ to 12,931’.  Vermejo Park Ranch’s Bison Division has a mission to promote the health and productivity of all native plant and animal species through ecologically sensitive and economically effective bison management, while protecting and preserving the unique genetics of the Castle Rock Herd.  

Breeding Herd

Vermejo Park Ranch seasonally rotates its bison herd from the high country in the spring, summer and fall to the prairie in the winter.  The high country habitat ranges from piñon-juniper and oak shrubland to alpine tundra and consists of 500,000 acres which is not fenced.  During this time, grazing management relies on low-stress stockmanship to herd the animals throughout the high country portion of the ranch, moving animals to under-utilized areas of better forage.  During the winter dormant season, the bison herd is rotated across 5 large pastures that comprise the ranch’s 60,000 acres of short-grass prairie.

The Castle Rock bison herd get their name from the unique geologic feature at Castle Rock Park, an area of the ranch which is at 8,200 feet elevation.  Castle Rock Park was “home” to these bison since the 1920’s.  They have survived this harsh high elevation environment with no supplementation for nearly a century while remaining sound and reproductively efficient.  The Castle Rock bison herd has Yellowstone origins with additional diversity of foundation bison genetics from two other herds.

The original animals of the Castle Rock bison herd were transplanted to Vermejo Park Ranch with elk from Yellowstone National Park 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 foundation Maxwell herd in Kansas were introduced to the Castle Rock herd.  Since that time, the herd has been closed to outside genetics.  This herd has always tested negative for cattle mitochondrial DNA.

The genetic diversity of the Castle Rock bison herd is maintained through a high bull to cow ratio.  The bull battery is made up of mostly 2- year old bulls of average weight and frame that are randomly selected, with a small number of 3-5-year-old bulls retained each year. All bulls are culled after their 4th breeding season to ensure broadened genetic diversity in the breeding.  Open cows may be culled in the spring each year, depending on drought, forage availability and other management considerations or remain in the herd if conditions allow it.  Replacement heifers of average herd weight are randomly selected from their cohort group to serve as breeding animal replacements.   

Calves / Yearlings

The cow calf pairs are kept together throughout the year, allowing calves to self-wean while in the cow herd.  Weaning percentage historically runs from 70% to 90% depending on the year and moisture patterns.  The calves are normally grazed with the breeding herd until they are removed as yearlings or two-year old.  During bison works held in February, the animals are tagged, dewormed, and are given vaccinations for: 7-way clostridial, 4-way viral, and Mycoplasma vaccinations.  Heifers are also vaccinated for Brucellosis. All calves have blood drawn for parentage testing and mitochondrial DNA analysis.

The calves, yearlings or two-year old’s that remain with the breeding herd are exposed to low-stress herding techniques while remaining within their family groups.  The whole herd is exposed to humans on foot, horseback and ATVs making them gentle and predicable to handle.

Health

Vermejo Park Ranch has never had a Mycoplasma bovis outbreak and the herd is considered naïve to the organism.  Despite this, all animals are annually vaccinated for Mycoplasma bovis.