Helicopters are commonly used to herd wild Mustangs into temporary corrals before they are loaded into trailers and hauled away. Each year, the Bureau of Land Management, or BLM, conducts wild horse roundups in their role as stewards of hundreds of millions of acres of public lands. Thousands of free-roaming appaloosas, pintos, bays and roans are removed from the range to control animal populations and diminish damage to grazing lands, the agency says. Animal advocacy groups are heavily engaged in trying to protect wild horses and burros and blame the BLM for managing the populations toward extinction with aggressive roundups. Critics of the roundups say the BLM often favors for-profit cattle ranchers that graze their livestock on the public land shared with the mustangs and burros. The BLM currently holds 47,000 wild horses in government holding facilities, far more than the 31,500 mustangs still left living in the wild. According to the BLM, in 2012, holding costs of $42 million devoured nearly 60% of the agency’s $72 million budget. Officials say there are still 11,000 more wild horses than public lands can accommodate and that their population, if left unchecked, can double in size every four years. About 700,000 privately owned cattle graze part-time on BLM lands.