Very often. Mine sometimes even peck at the egg to help the new chick along. They peep to each other in order to sync the hatch. (Late chicks will be slower to get food when in competition to the older ones. More than 2 days late is a huge window in baby chick time.) It's neat how mother nature solves this problem by having them all hatch at the same time even though the eggs are layed on diff days.