One evening just after sunset we had 3 raccoons trying to break into the coop. It was a bit early for them, but they were there nonetheless. The girls put up such a racket that I'm amazed the town cop didn't hustle over. They kept this up for 3 more days, long after the raccoons were gone....it sounded like the needle was stuck on the Egg Song record. The slightest thing set them off - wind rustling a bit of plastic, tree branches scraping the side of the house - they were totally stressed out and their alarms were stuck on overload. Not one chicken harmed, not one feather mussed, but they carried on as if those raccoons were right there in the coop with them and they were all going to die at any minute. Nobody says they don't' react to changes around them. I just don't believe they understand the concept of "mourning" as it pertains to the emotional loss of a loved one. If a chicken dies in the coop and no one takes it out, the others are more likely to pick it apart than mourn it.