The HMA covers 434,200 acres in southern Oregon, near the Sheldon National Wildlife Refuge, a recently established horse-free zone.
The AML is 250 and the stocking rate allowed by plan is 0.6 wild horses per thousand acres. As stated earlier, fractional stocking rates may signify large amounts of forage diverted to privately owned livestock.
The horses allowed by plan require 250 × 12 = 3,000 AUMs per year. The land must be able to produce at least 3,000 ÷ 434,200 × 1,000 = 6.9 AUMs per thousand acres per year to support the horses.
The HMA lies completely within the 575,495 acre Beaty Butte Allotment, according to page 28 of the EA. Map 2 in the appendices shows the arrangement.
The Allotment Master report from RAS provides the acreage and active AUMs. The average grazing season was computed from data in the Authorization Use report.
To fulfill the forage allocation for livestock, the land must be able to produce at least 26,121 ÷ 575,495 × 1,000 = 45.4 AUMs per thousand acres per year, reinforcing an observation made earlier that forage production goes up when land is designated for livestock. In this case, by a factor of 6.6.
The forage allocation for livestock inside the HMA is approximately 19,000 AUMs per year, according to the discussion on page 55 of the EA. The Beaty Butte permittees would have to place 3,106 cow/calf pairs inside the HMA to graze off 19,000 AUMs in 6.3 months, for a stocking rate of 6.9 cow/calf pairs per thousand acres.
These figures are compared in the following charts.
The HMA is managed primarily for livestock, with the horses receiving just 14% of the authorized forage, neglecting wildlife.
The stocking rate for horses is 8% of that for cattle.
The forage assigned to livestock would support an additional 1,583 wild horses, for a True AML of 1,833.
The current population, based on data from page 7 of the EA, is probably around 500 horses, well within that range, so there is no need for a roundup or darting program.
RELATED: History of Beatys Butte HMA.