Fold the microfibre cloth in 4 ways and try to lift the poop off, DO NOT WIPE OR SCRUB. This is because most birds will eat small stones to help grind up their food. These stones do not get digested, becoming a part of the poop on your car, so a wiping motion will create scratching. Each time you pull the cloth off, you will see the poop remnants in the cloth - don't wipe this back into the paint.
Always fold and use a clean section of cloth on your paint to minimise the chance of any more damage occurring.