Ma Eagle has just landed beside the nest to relieve Pa of the egg sitting duties. Pa takes off to go hunting and Ma carefully walks in to the nest to avoid harming her egg/s. You can see Ma rolling her eggs between her legs. "The purpose of this roll is to make sure that the lighter yolk does not rise to the egg surface and the delicate blood vessels that cover the yolk touch and stick to the shell surface, killing the developing chick." - David Hancock