Comparison of estimates to known abundance for aerial surveys of feral horse (<i>Equus caballus</i>) populations.

<p>Abundance estimates or change in abundance (black dots) and 95% confidence intervals for aerial surveys of feral horse (<i>Equus caballus</i>) populations in the western USA, using a hybrid double-observer method. Ranges of known population sizes are shown in green. Surveyed U.S. Bureau of Land Management Herd Management Areas (HMA): McCullough Peaks HMA, Wyoming (MCP); Sand Wash HMA, Colorado (SW); Cedar Mountain HMA, Utah (CM); and Little Owyhee-Snowstorm Mountains HMAs, Nevada (LO-SM).