For a quick estimate, convert the livestock AUMs to wild horses and add the result to the AML.
The 250 horses allowed by plan consume 3,000 AUMs per year. The HMA covers 193,255 total acres, including 176,227 BLM (public) acres.
The eight permittees receive a total of 23,906 AUMs per year according to Table 2.
The Allotment Master Report indicates a forage allocation of 23,103 AUMs per year across the two allotments. Both are in the Improve category and contain a total of 176,988 public acres.
The forage assigned to livestock, based on data in the EA, would support an additional 23,906 ÷ 12 = 1,992 wild horses, for a True AML of 250 + 1,992 = 2,242. This is the number of animals the HMA could support if it was managed principally for wild horses, as specified in the original statute.
The current population of 952 is well within this range, so there are no excess horses in the HMA and there is no need for a roundup or a fertility control program.
The 1,992 horses displaced from the HMA by permitted grazing represent 4.0% of the 50,000 animals in off-range holding.
The current AML corresponds to about 11% of the total authorized forage, neglecting wildlife, meaning the HMA is managed primarily for livestock.
Forage availability in this area is very high, about 152 AUMs per year per thousand acres, which would support a stocking rate of almost 13 wild horses per thousand acres!
For reference, the Virginia Range was carrying ten wild horses per thousand acres before the advocates got involved.
The target rate across all HMAs is one wild horse per thousand acres.
AMLs and stocking rates are small relative to the available resources because the bureaucrats put ranching interests far above those of the horses.