Depends how long its been on there etc, but when i had some on my roof it was rock solid and i mean ROCK i got the soapy water out, used a sponge to get what i could off then i found out wd40 may work.................... so i cracked that out and tried some on some tissue, and it bloody worked, and proper worked, it got every last trace of it off the paint work

Wipe over with some more soapy water and job done havent put any protectant on yet but no more bird mess

Not saying it will work because it depends how long its been there, but worth a try. Just make sure afterwards you give the area good wash to get the oil off