Am sure it is funny to see someone experience a bird-poo situation but it most certainly ain’t so if we’re the victim :p
I can’t prove it but I’m qute sure birds prefer shiny cars to do their business! Guys/Gals, check your cars all the time. If you see any bird droppings on your car, the wise thing to do is to “immediately” clean it. If you leave it there , you will have a serious problem especially after 30 to 45 minutes in the sun. Acids in the droppings will have become concentrated, eaten through the wax and started to stain or etch your car’s clear coat finish.
Fresh droppings can be wiped off with a damp cloth or sponge but if you want to be more certain, then mist and wipe the area with a spray wax or sealant to maintain your car’s protective finish but there’s seldom any lingering damage.
Of course if you are looking to for fresh coat of paint on your car, then you can always let it be.