I've seen fish heads and egg shells in our bird bath that crows have brought in from the neighbor's trash down around the corner. I think they like to dunk that stuff when they eat it.
I saw some birds (not sure which) bring stuff as offerings
little trinkets, stuff they likes sort of like a thanks, for the bath or seed etc.
we had a bird bath in-front of the house for a while,
I got tired of all the weeds, from their (seeds) droppings/their ****
we had a quite a few oddities showing up in the bird baths
my neighbor is glad it's gone now too
he's a Lt. Calif. Fish & Game Warden,
he has the same issue with the damn peckers as, I do
freaken' black Oaks/Acorns & damn Peckers they attract here,
are the real problem
they live in the trees right behind me, Sugar Pines
pecked the **** out of them for storage too
fortunately we now have Peregrines
& I hear a Red Tailed Hawk family, living back there now too
love the screeches the birds of prey make
fun to watch the peregrine swoop down & go after the peckers
poof & feathers fly