I have nest boxes for Blue Birds scattered around my property. I was working on a fence today and was taking a break and watching the blue birds feeding their young, both male and female were busy toting worms to the babies. Then I saw something I had never saw before, the male came out of the nest box with the spent egg shells and flew off went about 50 yards out in the field and dropped it. He did this four times. He would not throw the shells under his nest it might cause a snake or cat to investigate his nest. Nature is amazing.