Don't get mad, get even.
If a bird shits on your car, then track that sucker down, climb that tree, find it's nest, drop your drawers and let loose a good ol' fashioned yankee doodle aunt bea from mayberry cosmic shit.
Then get yourself a video camera to catch the bird's reaction when it returns to the nest and sees a great big steaming leftover corn kernel turd a-restin' in it's nest.
That'll teach them winged varmints!