There are three layers of forage demand in most HMAs: Horses, livestock and wildlife.
To estimate the carrying capacity, convert the forage assigned to livestock to wild horses and add the result to the AML.
The HMA is a subset of the Reveille Allotment, as shown in the National Data Viewer.
The HMA offers 138 × 12 = 1,656 AUMs per year on 104,500 public acres, or 15.8 AUMs per year per thousand public acres.
The allotment offers 25,730 AUMs on 657,520 public acres, according to the Allotment Master Report, which works out to 39.1 AUMs per year per thousand public acres.
Land that can only produce 15.8 AUMs per year per thousand public acres for wild horses can produce 39.1 AUMs per year per thousand public acres for livestock.
If the resource is evenly distributed across the allotment, the forage assigned to livestock inside the HMA should be 39.1 × 104,500 ÷ 1,000 = 4,086 AUMs per year, enough to support 4,086 ÷ 12 = 340 wild horses.
Therefore, the True AML, the number of wild horses the HMA could support if it was managed principally for them (as specified in the original statute) is 138 + 340 = 478, to be achieved by confining the ranchers to their base properties in a year-round off season.
The current population, thought to be 164 plus this year’s foal crop, is well within this range.
The Authorization Use Report indicates a twelve-month grazing season.
The HMA is managed primarily for animal agriculture, with cattle receiving 2.5 times more forage than the horses.
The roundup will bring forage consumption in line with the resource specifications of the land-use plan(s) and the fertility control pesticides should keep it that way for many years to come.
RELATED: Reveille Roundup Announced.
Western Horse Watchers Association 