One of my two four-year old hens has all of a sudden decided to take one big peck out of her egg just after she lays it. She makes a hole in the shell, but then she leaves the coop. She doesn't appear to be really eating it. This has been going on now for several days. I had three hens. One was taken away in the night by a raccoon (I believe), another has a problem with broodyness, now my third one, who was a pretty steady layer, is doing this! Makes me want to give up on chickens. Any advice would be appreciated.