Normal Growth Rate: Horses are a slow-growth species when it comes to reproduction. The gestation-period lasts over 11 months, and a mare produces just 1 foal. Gregg, LeBlanc, and Johnston (2014) found that the birth rate in wild-horse herds is almost 20%. Unfortunately, they also found that 50% of foals perish. At least 5% of adult wild horses also perish every year. Thus, the normal herd-growth rate for wild horses is only about 5%.

Fraudulent Growth Rates: Three herds were featured on the Advisory Board’s tour — Antelope Valley, Goshute, and Spruce Pequop. A review of BLM’s alleged growth figures for these herds showed biologically-implausible increases. From a combined total of 1,440 wild horses in 2013, BLM claimed the herds grew to 3,025 wild horses by 2016, a 110% increase. That would mean a 37% average growth rate, which is 740% times the norm. Moreover, if given a 37% growth rate, then to overcome foal mortality and adult mortality, the average birth rate would have to have been 84% — which is 420% times the normal birth rate. Ben Masters and fellow board members unknowingly “drank the Kool Aid” — they swallowed BLM’s propaganda. Truth be told, the range they toured had previously been overgrazed … by livestock.

Wild horses are underpopulated: Per BLM’s own geneticist, 83% of wild-horse herds suffer from arbitrary management levels (AMLs) set below minimum-viable population. For instance, the AML for Oregon’s Beaty’s Butte herd restricts the stocking-density to 1 wild horse per 7 square miles. If there are 2 wild horses per 7 square miles, BLM can technically declare an “overpopulation” because there is “double the number” that the preposterous AML allows. In contrast, BLM authorizes 119 cattle per 7 square miles. After eliminating 99% of the Beaty’s Butte herd, BLM replaced the wild horses with cattle to accommodate a rancher, who had secured a contract to supply grass-fed beef to an upscale grocery chain.

by Marybeth Devlin

Advisory Board Member for Protect Mustangs

Member of the Alliance for Wild Horses and Burros