You may want to check with your state wildlife officer first, (this could be considered as harassment of wildlife), but you may try a bear spray trap. Rig up a bear spray in a barrel, and when the bear trips the trip wire (or what ever mechinism you chose), it blasts them in the face. After 1 or 2 times, they get the hint and leave the area. Its a little less harsh, compared to .44mags and 375 rums going boom in the night.

This trick is done for trouble bears that are breaking into homes and stuff.
Again, this may be illegal in your area. 2 reason. 1. Harassment and 2. Baiting ofwildlife.