I have (had) a small flock of 5 ladies - 2 Buff Orpingtons & 3 Barred Rocks. I let them run free for a couple hours this afternoon (as usual) & then went to put them back in their run. When I offer them dried meal worms, they usually excitedly come running as fast as they can - today only 4 came. I found Pearl, one of my Orps, laying under a tree in the run. Initially I thought she was dust bathing, but she then began rubbing her head on the ground & about 30 seconds later was lifeless. She was a year old and seemed to be in perfect health. I am so saddened by the loss of my girl and am wondering if anyone knows what may have caused this?