I had a ceramic nest egg disappear once. Assumed a rat snake ate it. I felt pretty bad about that and stopped putting the ceramic eggs out there after that. I do get frustrated when the egg yield is low because the snakes get the eggs.
We had a rat snake (my husband calls it a chicken snake) return twice after being removed from the nest box and relocated. We knew it was the same one because it had a scar on its back. (Thus, the legend of "Scarback.") The first time, my husband released it on our property, about 1/2 mile from the coop. Scarback returned within about 2 weeks. The second time, we released it about 1 mile from the coop, across a road and on some undeveloped property. Scarback turned and was heading back in the direction of the coop before we could get the truck turned around. He was back eating eggs in about a month. The third time we released him about 3-4 miles away, again in a farm area. Haven't seen him back yet, but I wouldn't put it past him. It's been about 3 years now since we've seen him.
Right after that, my farrier told me a rattlesnake has a range of about 25 miles! Don't know about rat snakes. Now when I catch a rat snake in the coop, I release it in a state park about 10 miles from here!