The normative annual herd-growth rate is, at most, 5 percent. Gregg, LeBlanc, and Johnston (2014) found the average birth rate across wild horse herds to be just under 20 percent. But they also found that 50 percent of foals perish before their first birthday. Thus, the birth rate is just a temporary blip in the data. Starting with the net population gain from surviving foals (10 percent), and then subtracting a conservative estimate of adult mortality (5 percent), the expected normative herd-growth rate would be, at most, 5 percent. At that rate, it would take 14 years for a wild horse herd to double.
BLM falsely conflates the birth rate with the herd-growth rate. But, the birth rate and the growth rate are different measures. The birth rate must be reduced by the respective mortality rates to determine the population-growth rate. BLM’s error has been brought to their attention on many occasions. BLM’s persistent false and misleading representation of a 20 percent growth rate—times the norm—constitutes fraud, which violates Title 18 USC 1001 of the Federal criminal code.
Insufficient population results in a sparse, widely dispersed herd. BLM set an arbitrary management level (AML) for the Piceance-East Douglas herd. The population is restricted to a range of 135 to 235 wild horses. However, BLM manages down to the low end of the AML. Per the habitat’s 190,016 acres—297 square miles—BLM’s low-AML results in a stocking-density of one wild horse per 1,408 acres—over 2 square miles. That sparse population-level is not adequate to ensure genetic viability.
Reform is needed. BLM has already closed 246,054 acres—385 square miles—of what was originally wild horse habitat adjoining Piceance-East Douglas. Those herd areas are North Piceance (118,405 acres—185 square miles) and West Douglas (127,649 acres — 200 square miles). North Piceance and West Douglas need to be reinstated and repopulated with wild horses, as the Law originally intended.
Inequitable allocation of resources disadvantages the wild horses in their own habitat. Of the 58,725 animal unit months (AUMs)—grazing slots—available in the Piceance-East Douglas wild-horse habitat … 57,105—97 percent—are allotted to livestock; 1,620—3 percent—are allotted to wild horses.
Lagomorphs: BLM alleges “competition” between mustangs and livestock over forage. However, among the range’s dominant herbivores are the lagomorphs—jackrabbits, hares and cottontails. BLM neither determines nor factors in the lagomorphs’ forage-consumption. A recent study in Utah found that jackrabbits were eating 34 percent of the grasses on local grazing-allotments.
Locusts: In normal times, locusts—grasshoppers and crickets—consume 20-25 percent of the forage in areas where they are present. However, in times of outbreaks, they can eat nearly all of the green biomass. The USDA publishes an annual map showing areas of grasshopper-and-cricket infestation. The 2017 map shows massive outbreaks in Colorado, including the Rio Blanco County area. https://www.sidney.ars.usda.gov/grasshopper/Extras/map17.htm