Black bears are on the move in Grand Teton National Park and the reason is berry simple.

Park officials have closed most of a 7-mile-long gravel road accessing the south end of the park for two days now. The reason: Eight black bears are feeding on hawthorn berries in the area.

Bears eat as much as they can this time of year to fatten up before winter.

Park officials suspect a poor crop of huckleberries this year is causing bears to feed more on the hawthorn berries that grow near Moose-Wilson Road.

The road is a popular place to bike and hike but park officials say there are just too many bears in the area for the public to be safe.

All other routes into Grand Teton remain open.