The management plan assigns 363 × 12 = 4,356 AUMs per year to the horses at the upper end of the AML.
Livestock receive 19,758 AUMs per year per Table 2.1. The total authorized forage inside the HMA is 4,356 + 19,758 = 24,114 AUMs per year, neglecting wildlife.
That means the horses can consume up to 18% of the authorized forage, sometimes referred to as ‘their food.’
The proposed action will gather the HMA to the lower end of the AML, leaving around 163 horses. Growth of the herd will be minimized with contraceptives.
The remaining horses will require 163 × 12 = 1,956 AUMs per year, just eight percent of the authorized forage, on land set aside for them.
AUM curtailments, if any, can be relaxed after the roundup, as forage consumed by ‘excess’ horses shifts back to the ranchers. This ‘thriving ecological balance’ should prevail for many years, thanks to the fertility control program and its adherents.
The forage assigned to livestock would support an additional 1,645 wild horses, for a True AML of 363 + 1,645 = 2,008.
The current population of 828 is well within this range.
If the HMA was managed principally for wild horses, per the original statute, there would be no need for a roundup and fertility control program.