I had three egg eaters out of my five hens and I managed to break them of that habit. Here are the things I tried since I could not use a roll-away nest because of the design of my first coop. The next one I make will have roll-away egg collection as the first feature I design. Live and learn I guess.
*Side note*: if you laying hen is not laying in the nest box, she might not know that it is where her eggs will be "safest". Make sure that the nest box is dark all day, ease for her to get into, and for good measure through in a false egg so that she is manipulated into thinking "Hey, other hens lay here, it must be a good spot". You can also lock up you hens for a few solid days in the coop (if they aren't eating the eggs) to help them get the idea.
-I filled blown out eggs with mustard, Tabasco, wasabi, and a few times I tried soap. None of these things put them off eating the eggs.
-I put wooden eggs in the boxes, but that didn't stop them. I tried marble, but that too didn't stop them.
-I sprayed the fake eggs with that bitter apple, and put it on some empty shells. Didn't work.
The only thing that eventually did stop them is that I would wait around the coop at the times I knew someone was going to lay (it was my summer vacation so I had the time, you might not), and as soon as it dropped I would open the coop and snatch it away. I would then hold the egg out in front of the chicken (known egg eater or not) and wait for them to make a move to try and eat it from my hand. As soon as they moved, I would flick their head or "peck" their head with my finger nail.
I'm not sure if you could call this Pavlovian conditioning that if they eat the egg they get a pain stimulus; or if by pecking their head the way the top chicken on the pecking order would I was telling them "Hey, I'm the top dominant bird so I get the eggs, not you." Either way it only took two weeks of doing this and I haven't had a single egg eaten since. It also helped that I started giving them greens, kitchen scraps, weeds, etc. for their run a week later because I really believe that they were bored.
