I don't know. We had some storms come through last night. I put them in the coop and shut the door to keep them safe and from getting rain in the coop. I went to let them out this morning and found her. I am so heart broken. I didn't find anything wrong with her. She seemed fine yesterday. I hope it wasn't because she wasn't getting enough to eat. She seems the same size as her sister. I am heart broken. I planned on going to the store today to get the stuff to tube feed her. She was not just a chicken to me, she was a pet, followed me everywhere. She would rather be with me than the flock. She was the most curious. This is my first flock. I never thought I would like chickens but through her God taught me how amazing they really are. She was so great and I am going to miss her so much.