My hen is about two years old. She's missing a ton of chest feathers, and the floor of the coop is littered with them. She seems to have stopped laying. She isn't sitting on a nest or moody. There was a dead mouse right outside the coop. Did something kill the mouse and scare her??
The mouse may have attacked her.How big was it?What did its scars look like?Do you have any other hens.She may be molting either that or others are picking on her (Of course if you had others.)Hens can lay through out molting,but not all.And your positive she's 2 years?