I use clay and polishing stuff that I got at Griot's garage
Paint Cleaning Clay - Paint Cleaning Clay - Polishing - Car Care - Griot's Garage
With some of the other stuff that is available there, you can probably get the bird crap off. I bought quite of bit of stuff from Griot's (orbital buffer, various polishing compounds, detailing stuff) and use it to keep the finish on my car looking sweet. I think the clay from Griot's will probably be of better quality than what you have. Give it a try.