Our barred rock died today. She was hatched June 2008. Came to live with us in November. (We are brand new to the backyard chicken thing.) They live in a secured run. The other 2 in her flock started laying about 3-4 weeks ago, but she did not. About 1.5 weeks ago we noticed that she had a very dirty vent--it appeared she was possibly suffering from diarrhea (?) Last week, we started asking fellow chicken owners about it, because she was looking a little listless too. Yesterday afternoon, when I went down to feed and check on them, she was in the coop--sitting on top of one of an egg of a coop-mate. I had to move her to get to the egg, but she got up and went out in the run. Then, today, my husband got home from work and went down there--she was dead (laying half in and half out of the coop with her head buried.) Does anyone know what might have caused this? How much do we need to worry about the other 2? They seem fine--are as clucky as ever and continue to lay.