Baby turtles seem to despawn when the player leaves the general area. I had 2 turtles eggs in a fenced in location, where it was safe from zombies. After the eggs hatched, the 2 baby turtles were no where to be found. Fully grown turtles are fine, but babies seem to consistently despawn. I've seen other reports of this, but it doesn't seem to have been properly addressed and other reports have been closed.