My son called me out to the yard today to listen to one of the hens... he said that she wouldn't return to the run and that she "sounds like a machine gun" and sure enough, she did! It wasn't her breathing though, it was like she was talking in really short, rapid clucks. After observing her behavior we noticed that she was extremely interested in an area under the deck where two (what appeared to be) mouse holes were. Do chickens HUNT? I mean, we see them scratch for bugs all the time, but they always get their prey almost immediately. Is it possible that she saw a mouse and was excited?