The 150 horses allowed by plan require 1,800 AUMs per year.
The True AML, the number of wild horses the HMA could support if it was managed as specified in the original statute, can be found as outlined in this post.
Section 3.2.2 in the Draft EA for resource enforcement actions in Three Fingers and Jackies Butte identifies two grazing allotments that intersect the HMA. The Western Watersheds map shows the arrangement. Click on image to open in new tab.
The Allotment Master Report provides the active AUMs.
Table 5 in the EA indicates that 28% of Board Corrals is inside the HMA, along with 39.2% of Three Fingers.
The forage assigned to livestock inside the HMA is 1,172 + 3,913 = 5,058 AUMs per year, assuming the resource is evenly distributed across the two allotments.
That amount would support 5,058 ÷ 12 = 423 wild horses.
The True AML is 150 + 423 = 573.
The current population, thought to be around 280 adults according to Section 1.2 of the EA, is well within this range. There is no justification for a roundup or fertility control program, which the Proposed Action would implement.
The stocking rate at the new AML, based on the acreage of Section 1.2, would be 573 ÷ 62,508 × 1,000 = 9.2 wild horses per thousand acres.
Given that the horses currently receive 26% of the authorized forage, neglecting wildlife, the HMA is managed primarily for livestock.
The 423 horses displaced from the HMA by permitted grazing represent about 0.8% of the 55,000 animals in off-range holding.
RELATED: Status of Three Fingers and Jackies Butte Allotments.