I came home this afternoon to find a 1 1/2 year old hen dead in the pen. Her neck does not seem broken and there are no wounds. She did not behave like she was sick and everyone else is acting fine. She is in a large pen with 11 other hens and two 6 month old cockerels. The two cockerels are not full grown and are lower in pecking order than half the mature hens. I have not seen them behave extra aggressive. I jus cannot figure out what could have happened. Oh yeah, she is a red sex link. Do chickens have heart attacks?