Difficult to remove dried bird droppings/poop on car

Just a reminder to myself bird droppings isn't good for the car paint. After leaving it a week without washing the birds' poop becoming too stubborn to remove and i have yet to find any detergent or chemical that can clean it effectively. The possible caused of this is possibly the fruit latex mixed with acid from the bird stomach and by the help of the sun heat the stain is bonded with the car paint. This is definitely something to avoid at all cost especially under the trees with fruits ;).