Nestled between the Big Horn National Recreation Area and the Pryor Mountains of the Custer National Forest is the 38,000-acre crown jewel of wild horse management areas: the Pryor Mountain Wild Horse Range.
One of the first two wild horse sanctuaries in the nation, the Pryor range was established in 1968 (three years before the passing of the Federal Wild Free Roaming Horses and Burros Act) to protect the iconic Colonial Spanish horse genetics preserved in the herd.
Genetic testing shows the herd is one of the purest strains of the original horses brought to the New World by Spanish explorers. Their escapees became the herds that supplied Native Americans with the original “Indian ponies.”
Some of the horses still exhibit primitive “Old World” markings such as dorsal stripes on their backs and tiger stripes on their rumps. Many of the other markers of the old world origins such as small heads, convex ears and smallish body size (many weigh less than 900 pounds) are prevalent. When the herd is reduced, those without Colonial Spanish traits are among the first selected for culling.
While many of the federal wild horse ranges throughout the western United States are faced with the daunting task of warehousing thousands of unwanted mustangs, the Pryor herd seems to always have adoptees for the gentle, strong-hoofed, surefooted equines.
By law the herd is supposed to be between 90 and 120 animals. Some geneticists warn that a population below 120 will cause inbreeding and a lack of the genetic diversity required to maintain herd health.
The last population census claimed 160 horses on the range. The population is slowly creeping up each year by five to 10 animals. There will be a recount in June to correct for those that did not survive the winter and count new foals.
On average, 60 percent of the foals survive their first year. The main cause of colt mortality is abandonment, being stepped on, falling off the prominent cliffs, winter and drought. Their main predator, once the colts are old enough to keep up with the herd, are cougars.
The desired gender makeup of the herd is 50/50 but the current make up is 45 percent male and 55 percent female. Of the horses above the age of 20, four are stallions and 17 are mares. In the breeding population, 26 are stallions and 26 are mares.
To keep the population in check, mares below the age of 5 and above the age of 10 are darted with Porcine Zona Pellucide as the preferred method of birth control. The mares are approached on foot and darted in the hip at about 30 yards.
The only complications seem to be that the mares live longer and occasionally develop temporary nodules at the injection site. Without fertility control, there would be an annual herd growth of about 25 horses; with it, the average is about 12.
According to Jared Bybee, the wild horse and burro specialist with the U.S. Bureau of Land Management Billings Office, the desired grazing impact is to consume no more than 45 percent of the available forage based on dry year growth patterns. However, the range is currently utilized from 21 percent to 89 percent, which can cause soil erosion.
Specialist Bybee, who has a degree in range management, says that with the law not allowing cross fencing, or herding of the horses, the only option is to “give them a reason to graze somewhere else.” Acknowledging that the older horses will always follow the snow line up to high grazing, he hopes to get the younger horses to frequent the 10 new water developments and use lower grazing opportunities.
While the Pryor herd boasts among the purest strain of Spanish Colonial genes in America, the horses are not pure. A stallion from Wyoming in the late ’80s was introduced to add to genetic diversity in the herd, which was the last intentional introduction. The entire range is fenced and, despite rumors to the contrary, Bybee maintains that no mustangs roam the national forest adjacent to the sanctuary. The lesser genetic strains that show up in the tests include common light riding and racing type ranch horses used over time. Prevalent in these is quarter horse genetics.
Of the BLM’s $300,000 budget for this area, only $85,000 is dedicated to range projects, fertility control and water projects on the 38,000-acre range. The viewing of the horses is a growing destination for many on vacation and locals. When the horses are at lower elevations, they can be seen from all-weather roads in the Bighorn Canyon.
Later in the season, many Montana families mount four wheelers and 4x4 vehicles to go up the Pryor Mountains and drop into the top of the range, hoping to catch a glimpse of the West’s living history.