Where's the Bark?

I know you should "be careful what you ask for" and all, but Miner doesn't bark. We think he might have been mistreated when he was young for barking, because the first few times we heard him bark he cowered. So we try to give him plenty of positive reinforcement when he happens to bark today.

This morning, Miner was laying by the front screen door, looking outside as usual to see if any squirrels happened to come into the yard. Squirrels have come as close as the top step by the front door before. (I think they are taunting him.) We hear Miner growling at something. Not a very loud growl, just a low rumble. David walks over to the door quietly so he doesn't scare whatever it is off. He looks around and busts up laughing. Miner was staring and growling at a fly that was hopping around on the door mat. I wish we had been able to get it on video.