Hope it works for you! Try it a couple days in a row too, it might take quite a bit of scratching for them to loosen it up enough to easily pick up or rake up the pieces.
Even if it doesn't work, I think they enjoyed it. They almost never get scratch. I'm too cheap. LOL! Although, they got bored and are now back in their favorite part of the yard hanging out again. Silly birds - creatures of habit. I don't think I have enough chickens to do damage to my lawn. Maybe I should get more...

