Idaho Fish and Game said it is restricting ATV's and motorcycles to roads in 30 hunting units. It is called the motorizing hunting rule.
Gregg Losinski, who works at the agency, said hunters can still hunt on their ATVs, but they can only do it from a motorized roadway that can handle a full-sized vehicle.
"If you go off to a trail that is legal for four-wheelers but is not able to sustain a full-size vehicle and you're in that area where those rules are in effect, that means you can't hunt on that ATV while you're off that main road," he said.
He said it is important for hunters to know what hunting unit they are in. There is more information here: http://www.trails.idaho.gov.