another thought. if you store or keep food in coop (ever) or run at night remove it. the bear wants the food, not the birds. but they will take chase after birds once in the coop.
That will be difficult as you need about 7000v or 1j to be effective on bear, and that may not be enough to get through their very thick insulated coat.
luckily bear are curious and sniff everything so use that to your advantage. My suggestion is to get a 1j fencer, three lines with lowest 6in...