Well sorry I can't help you out much but I have a similar problem with one of my trees.
I feed birds & love birds and they (especially morning doves) nest in my trees. No biggie, they have for years. Except they have alwyas stayed away from my front tree. Well this year they decided that the front tree is great. I am not sure if they have a nest in it as the tree is pretty big & I can't see a nest. They may just be hanging out in there. I think a combination of birds visit the tree (robins, morning doves, etc)
But there is bird poop everywhere. Now this normally would not be a problem but it is right above my porch, patio, entrance door, driveway, walkway & car! And I mean everywhere!
Yup you guessed it, I & visitors get lovely white & black "presents" dropped on us daily!!!! Also my walkway, porch & car is a mess, bird poop everywhere!!!!! This is rediculous, it looks as if I have a heard of seagull living right above me.
I did have the tree trimmed slightly but that obviously did not disturb them.
Does anyone have any ideas on how to keep the birds away from this tree?