bird food

I rode my bike around the neighborhood to a few of my favorite spots. I'm standing under a forest of trees that was full of birds and I hear rain but feel no water. There above me are the birds pecking away at the acorn pods still hanging on the tree and from the pods small pieces are falling down to the leaves on the ground making the rain sound. I couldn't figure this out until I uploaded my photos and saw the pieces of pods the tiny bird was pecking on.

can you see the small specks under the bird in the middle of the 3 birds?
I'm always learning about nature from nature.