“More of a general question really, why does bird poo always seem to have a black bit in the center?”
Bird’s don’t wee, they only poo. Or, more accurately, they do both in the same bundle. So the white bit is actually the wee, and the black bit is the poo.
Of course, my older brother had me convinced it was vanilla ice-cream with a chocolate chip. But one lick, and I knew he was wrong.