Horses have roamed free for decades on old surface mines in Eastern Kentucky, but with unchecked breeding and owners apparently turning out more mares and stallions in recent years, the population has increased to the point of concern, according to animal-welfare advocates.

The horses can endanger themselves and drivers by wandering onto hilly roads, and face untreated health problems and potential food shortages in the winter.

“There’s a problem that is growing,” said Lori Redmon, head of the Kentucky Humane Society. “There are some sites that are currently not able to sustain the horse population.”

The horses roam on mined, unfenced areas in several counties, including Knott, Breathitt, Leslie, Martin, Magoffin, Perry, Floyd, Harlan and Bell.

In surface mining, companies blast the tops or sides off mountains to uncover coal seams, then plant vegetation in reclaiming the sites. That has created tens of thousands of acres of relatively level land where horses can graze.

It’s not clear how many horses there are on mined sites in the state’s eastern coalfield.

David Ledford, head of the Appalachian Wildlife Foundation, said he’d heard an estimate of 3,000 to 5,000, but noted there have been no formal surveys.