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Picture courtesy of Jean Bilodeau taken Aug. 2003 at the original gather of the Carter Mustangs.

What is a Carter Reservoir Mustang?

I had heard about the Carter’s, two of my clients (Bonnie & Robert)  have some Carter’s and had told me they were rare and hard to find.  I hadn’t paid much attention at the time, but now I was interested in finding out as much as I could.

After doing a lot of internet research I found that back in 2001 blood testing of Mustangs gathered by the BLM was in part to determine historical origin of the herd. The following is taken directly from the “Procedures for Collecting Blood Samples from Wild Horses and Burros for Genetic Analysis” document.

During the next four to five years all HMA’s will be gathered and data will be collected on Wild Horse and Burro populations to facilitate preparation of Population Management Plans (PMP’s). Blood samples for establishing baseline genetic data should be collected from horses and burros in each HMA as gathers are accomplished.

The test will consist of looking at 29 systems (17 typing and 12 DNA). The data will be compared to similar data from both domestic and other wild horse/burro populations. The primary value of this initial data is a baseline against which future samples can be compared to identify genetic drift. Diversity can be determined; herds may be separated or combined for management based on the data, rare alleles identified and a determination of founders (historical origin of herd). A report on the analysis will be provided by Dr. Gus Cothran, of the University of Kentucky, that will detail procedures, findings and recommendations.

Samples will be collected on the first gather of an HMA after October 1, 2001, unless an area has been adequately sampled within the last 10 years.

The Carter Reservoir Mustangs were gathered, the one and only time, in August of 2003. Making them part of the Genetic testing.  Results of the genetic testing showed, according to Dr. Corthran, “Based upon the combination of the similarity analysis and the variants present in the herd, it appears that the Carter Reservoir herd is derived from North American stock but that there is a Spanish component that is not through the North American breeds... The herd is likely derived from North American stock but it does appear to have some Old Spanish ancestry. “There are only four known markers that absolutely indicate Old Spanish ancestry. The Carter Reservoir herd has two of these, plus a third that is "probably" indicative of Old Spanish ancestry. It appears to be a stable herd over recent years, with no recent introductions of new stock. Dr. Cothran, expresses concern over the extremely low Area Management Level, stating that genetic variability is likely to decline rapidly.”  (As written by Nancy Kerson @ Mustangs4us.com)

There are other Mustangs with Spanish Ancestry markers such as the Kiger's, Sulphur Springs HMA, PryorMountain and Cerbat.  According to D. Phillip Sponenberg, DVM, Ph.D. Author of Equine Color Genetics, March 03, “The BLM also finds it easier to adopt out this type of horse (Spanish Mustang) rather than the usual crossbred type. If any other feral Spanish herds remain besides these four, they are probably very, very few in number.”

And he was correct.  When the Carter Reservoir Mustangs were gathered in August 03, there were around 200 gathered and approximately 35 put back in to maintain the wild Carter herd.  Making the original gathered Carter Reservoir Mustang highly sought after, rare and hard to find.

Carter Reservoir HMA​