But wow, 21 days is a lot of time for predators to get at an egg.
Well, that's a problem, but it kinda goes with the territory when you start farming or homesteading. Any livestock you keep has to be protected from predators, including human ones, and anything you grow has to be protected from wildlife and your own livestock.
We used to shut the chickens up in the henhouse overnight (they settle in around dark), as except for feral dogs the predators are almost entirely nocturnal. Once in a great while a 'possum would get in and the chickens would raise hell until someone would come out and off it with a .22 pistol.
modified by franksolich to correct minor formatting error; sorry for the intrusion