If washing wont take it off nor will some quick detailer/wax cut it. Then it has etched the clear and you will have to buff it out. I would look at getting the Meguiars buffer to buff it out. It is a little cheaper compared to getting a porter cable or the like. Any dual action polisher will work. Or take it to a professional detailer to have it corrected. Good luck...I hate birds oh and wait til next Spring you will hate bee's too..they like to poop on your car as well.....I suggest next morning sit on your porch while eating a plate of scrambled eggs to show them birds you mean business!
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Amazon.com: Makita 9227CX3 7-Inch Hook and Loop Electronic Polisher-Sander with Polishing Kit: Home Improvement