A fox recently got smarter than the fence. He ended up killing 10 – 15 birds before we fixed the problem. I raised the height of the gates and ran three strands of electric wire around the top of the pen. When I plugged the charger in and grabbed a hold of the wire I was shockingly disappointed. There wasn’t enough kick in the charge. I thought it was a bad connection to ground so we buried several old disks wrapped with copper wire in a hole. I was pleased with the idea and implementation, but in the end it didn’t help.