I second Spensar's post. We have a bunch of Grackles that nest in our arborvitaes, and use our pool as a drop off point for their poop. I just scoop it out of the pool every morning, and hose off the patio. The good news, as Spensar says is that the behavior only lasts 2-3 weeks. Once the babies are gone so is the dive bombing poop. I'd rather live with this inconvenience than remove the bird nests.

Tom