My hens have been ravenously hungry lately and they are all pretty fat, they are over 3 years old now and within the past 2 months 4 have died. They all (including the ones that died) showed no signs of illness. The hens were fine then a few hours later they where dead. Could they have a disease Im not picking up on or is 3 just old for a hen. Also they all have been eating, drinking, being social, and their poops look fine. Anyone have a clue what could be happening to my poor hens.