I wonder if there is any credibility to this, as from what I understand; pooping for birds is involuntary.
Edit: 1140 cars I feel isn't a sufficient enough sampling, with only 3% of silver having crap on them, my pewter s10 is in that 3%...all the time. Or it could just be a highly biased sampling. I think they should replicate the study a few dozen times. That would give us a better idea as to whether birds pooping on certain color cars more often than others really isn't a stochastic variable as to whether car color is actually a catalyst, giving birds more desire to poop on those color cars, or is it just those colors cause the birds to poop more readily.
I feel further research on the matter would be necessary to get to the bottom of this dilemma, so long as the matter merits the resources.
Another edit: forgive me if I am being too analytical with this study, I know it's just for fun, not trying to spoil it.