Genetic diversity in Colorado’s Pryor Mountain wild horse herd has declined, a geneticist says.
The Cloud Foundation blames roundups staged by the Bureau of Land Management for the decline.
For over thirty years, the genetics of the Pryor Mountain Wild Horse Herd have been tracked by equine geneticist E. Gus Cothran.
His first revelations linking the herd to the horses of the Spanish Conquistadors and Old World Iberian Horses were cause for celebration among local supporters of the herd, who long believed that the appearance of some Pryor horses were indicators of their Spanish ancestry.
Cothran indicated in earlier reports that the genetic diversity of the herd was good.
But his latest report, issued on August 22, reveals a herd at risk of losing genetic variability.
Cothran said that “compared to past sampling of this herd, variability levels for all measures has been in decline”.
He said the expression of the Spanish heritage is “stronger than seen recently”, but it could represent “the very beginning of evidence of inbreeding”.
The Cloud Foundation’s executive director, Ginger Kathrens, whose documentaries about the Pryor stallion, Cloud, brought world-wide attention to the herd, said she had feared the loss of genetic diversity since 2009, when the bureau announced plans to reduce the herd to population levels not seen in many years.
In response, the foundation filed a lawsuit against the bureau in 2009, challenging what it believed was a dangerously low appropriate management level (AML), asserting that such low population would damage the genetic diversity of the herd and put the animals at risk of inbreeding and eventual die-off.
The lawsuit was expanded to include the Forest Service in 2010, when it announced plans to build a two mile long, buck and pole fence on the border between bureau and Forest Service lands atop East Pryor Mountain.
The fence was completed in 2011 and denies wild horses access to thousands of acres of high quality, late-summer and fall meadows, the foundation says.
The litigation is still pending in Federal Court and it is believed that a verdict will be rendered before the end of the year.
“We’re at the point where it is imperative that the Bureau of Land Management work closely with both the Park Service and the Custer National Forest to increase the range for the Pryor Mountains,” Kathrens said.
“Unless the range can be expanded it will be difficult to allow for a significantly larger population.”
Cothran concluded his Pryor report: “The best way to maintain the current levels [of genetic variability] would be to increase population size if range conditions allow.”
The foundation said the problem of declining variability was not unique to the Pryor Mountain wild horse herd.
More than 70 percent of all western wild horse herds were managed at levels under 200 horses and faced the same threat, the foundation said. However, most herds occupied much larger acreages, but competed with privately owned livestock.
On these ranges, the wild horses receive less than 18 percent of the forage, with the rest available to livestock.
Kathrens called for more forage to be allocated to mustangs.
“If BLM continues their business-as-usual approach to wild horse management, we will begin to see significant inbreeding,” she said.
“I have been talking about the need for larger herds in order to maintain genetic viability for 15 years. Maybe now, with this very clear report on Cloud’s Pryor Mountain herd, mustangs will actually be given a fair share of forage on their legal ranges.”