I had considered and always thought that the tossing of bits of hay and leaves over the back was a misplaced/poorly timed effort to disguise hen or nest from predators. A while ago, I read someone's statement that wild hens would tuck bits of dried grass and leaves in their feathers when heading to the nest. When she settled on the nest, they'd fall out, and she'd arrange them into her nesting materials. Either theory makes sense. Wouldn't it be great to be able to read the thoughts of any animal??? I will often see eggs in the nest that look like they have been deliberately covered with hay. I had also read that the egg song when sung after laying was the hen's way of finding flock members after she finished laying. This also would make sense... the flock would continue to forage when a hen goes to the nest to lay. When she's done, she would sing the egg song, and flock members would answer back to make it easy for her to find them. I do know that some of my birds will sing the egg song when they get separated from the flock when they are out free ranging. Usually, the roo will go running to the singing hen.