A chicken who eats eggs from the nest is not a common problem, but it does exist. For obvious reasons this is a bad habit that needs to be addressed ASAP. If you don’t, the other members of the flock will soon be helping themselves to the goodies too.
There are a few things to try, but in my opinion they all take too long and there’s no time to waste. Chicken training has a rather poor success rate so let’s forget that too. What chickens are capable of is making choices, they know what they like and what they don’t.
We already know they like what’s inside fresh eggs, the trick is to change what they like into something they HATE. How?
Take a thumb tack and poke a little hole at each end of a fresh egg. Blow at one end of the egg until it’s empty, then squeeze yellow mustard into the egg and place it in the nest.
Chickens hate mustard, once they find it in an egg it will become something to avoid. Just make sure you stay on top of egg collection for a few days.
For the less determined chicken, removing all the hay or bedding from the nest is sometimes enough to discourage egg eating. An egg that rolls is harder for them to peck at, and often just not worth the effort.
Try one way, try the other, or try them both at the same time, just nip this problem in the butt before it becomes a bigger one.