My Buff Orpington was a year old. Last weekend my husband let the chickens out of their run in the morning. It was a beautiful day; all of the chickens seemed fine. I saw them at 2:00 in the afternoon. We had to go out at 4:30; so we went to put all the chickens back in the run. One of my chickens was sitting by herself and would not come to me. I went and picked her up and put her in the run. She stood up for a minute with her tail tucked under; and laid back down. I decided to let her rest and check on her when we came home. When we came home she was dead. All of my other hens seem to be healthy. I never had soft eggs so I don't think it was egg binding. I don't know if she may have ate something she shouldn't have in the yard. Has anyone ever had an unexplained chicken death.