SALT LAKE CITY (AP) — The federal agency charged with managing wild horses and burros that roam freely across 11 Western states should consider sterilizing some mares to control booming mustang populations and protect rangelands, a citizen advisory panel recommended Tuesday.

The Bureau of Land Management has long struggled with how to manage growing horse herds on public lands, which can double naturally within five years if left unchecked. Horses have been injected with drugs and vaccines to slow reproduction and rounded up for adoption, but the agency currently has more horses in captivity than are left roaming the range, forcing the emphasis to shift to population control rather than roundups.