I have 11 RIRs. They are 13 months old and started laying last October. They have all been in good health and other than some of the hens pecking feathers off some of the other's heads, they get along well. They have a good-sized coop and an enclosed chicken run outside. They are on regular "layer mash" and receive treats (weeds/grass I pull from the gardens - no pesticides ever used and sometimes loaves of bread with seeds in it). On Saturday the girls were out and all seemed as normal... dust baths in the dirt outside, pecking through the dirt and gravel, etc. On Sunday my husband checked on the chickens and he didn't notice anything out of the usual. Yesterday (Monday) I took some treats out to the girls in the run and noticed that some of them were in the coop (which isn't unusual). I sometimes shoo them all outside, so some of them don't miss out on the treats... which they really enjoy. As I was doing a headcount, I noticed one of them were missing, but I didn't see her in the coop.... until I stepped inside. I found one hen dead on the floor of the coop, about a foot away from the raised feeder. She wasn't in rigor (stiff), but a portion of her head had been pecked/eaten away. There was no blood to be found, though... which I thought was a little strange. None even in the straw around her. I did notice what looked like a tear in the skin underneath one of the wings (as if it were in the armpit)... but again, no blood. Our coop is secure (but we have had some rats get in on occasion, which we are addressing... via cats and shoring up the coop more) so I know it wasn't a raccoon or other predator like that. One note about the girl that died. She was "different" from the other hens. When all of the hens matured last fall, their combs grew to their "adult" size and got a dark red when they started laying. Most of them are "trim" in the traditional sense (not round birds). The one who died; however, was different in that her comb never grew at all. It looked like it did when they were chicks. The tiny amount of comb she did have never turned the dark red color... it remained a lighter shade. Her comb wasn't small from pecking at it... in fact, she was never picked on by the other hens at all. In addition she was a "rounder" bird than the others. Her personality was a little different in that she was always a bit more stand-offish towards people than the other birds. I don't know if her comb/body style had anything to do with her sudden death... but I can't think of any other reason why she died. They all are healthy eaters/drinkers and I don't seem to have any issues with parasites that I can tell. I checked on the girls this morning and they all seem to be the same as always... they hopped out of the coop and into the run with the same excitement and vigor as always. So I'm throwing this out to everyone... any thoughts or ideas about the cause of her death? Note: I did not do any inspection of depth post-mortem and she was burned by funeral pyre last night (I didn't want my outdoor cats or other critters to mess with the body... just in case she was sick) so I'm not able to do any inspections anymore.