Statistical analysis for 2024 survey of burro abundance in Black Mountain, Cibola Trigo, and Chocolate Mule Mountains Herd Management Areas

In November 2024, Bureau of Land Management (BLM) personnel conducted simultaneous double-observer aerial surveys of the wild burro populations in most of the Black Mountain Herd Management Area (HMA) and Cibola-Trigo HMA, portions of Chocolate Mule Mountains HMA closest to the Colorado River, and nearby lands. 

Surveys were conducted using methods recommended by BLM policy and the National Academy of Sciences with detailed methods. Horses were also surveyed as part of this survey effort. Two helicopters were used to survey this area due to its large size. 

These data were analyzed using methods to estimate sighting probabilities for wild burros, with sighting probabilities then used to correct the raw counts for systematic biases (undercounts) that are known to occur in aerial surveys, and to provide confidence intervals (which are measures of uncertainty) associated with the abundance estimates. However, other studies indicate that even such estimates are at least 25% lower than true burro herd size.