How Many Wild Horses Can the Callaghan HMA Support?

The HMA overlaps the Austin, Grass Valley and Simpson Park allotments, with 51% in Austin, 42% in Grass Valley and 7% in Simpson Park according to Table 5 of the Final EA for the Callaghan Complex.

The 237 wild horses allowed by plan require 2,844 AUMs per year.

Austin offers 14,478 active AUMs on 235,185 public acres, equivalent to 5.1 wild horses per thousand public acres.

Grass Valley offers 17,701 active AUMs on 267,201 public acres, equivalent to 5.5 wild horses per thousand public acres.

Simpson Park offers 3,406 active AUMs on 96,818 public acres, equivalent to 2.9 wild horses per thousand public acres.

These resources are present in the HMA, assuming they’re evenly distributed across the allotments, but they’ve been assigned to livestock.

To estimate the carrying capacity, shift them back to the horses. Forage assigned to wildlife stays with wildlife.

The HMA covers 152,726 public acres so the forage allocated to the Austin permittees inside the HMA should support 152,726 × .51 × 5.1 ÷ 1,000 = 397 wild horses.

The forage allocated to the Grass Valley ranchers should support 152,726 × .42 × 5.5 ÷ 1,000 = 353 wild horses.

The forage assigned to the Simpson Park ranchers should support 152,726 × .07 × 2.9 ÷ 1,000 = 31 wild horses.

The HMA should be able to sustain 237 + 397 + 353 + 31 = 1,018 wild horses (4X AML) if it was managed principally for them as specified in the original statute.

The new stocking rate would be 1,018 ÷ 152,726 × 1,000 = 6.7 wild horses per thousand public acres.

Your faithful public servants claim that public lands in the western U.S. can only support one wild horse per thousand acres.

The allotment master report puts all of the acreage in the Improve category.

Austin has more AUMs in the suspended column than active, while everything is active at Simpson Park.

The allotments would not make a good wild horse preserve because they overlap areas identified for wild horses and there is more than one authorization attached to each, so you’d have to acquire or control several base properties to access all of the AUMs.

Simpson Park contains Spencer Hot Springs, a water source for the Hickison burros.