Does anyone know how to get rid of hundreds of blackbirds that roost in evergreen trees and leave droppings?

everywhere? there is so much bird crap the trees look like there is snow on them and all over the ground.Does anyone know how to get rid of hundreds of blackbirds that roost in evergreen trees and leave droppings?
It is a long and dragged out process and according to the link below it involves in some states permission to use certain methods.


I've heard of the pie pan in the trees, I've also heard it doesn't work.


I've heard of hanging life like looking rubber snakes in the trees and those outdoor mechanical owls. Below is a link for the owls some are stationery and some are mechanical.


http://www.nextag.com/Easy-Gardner--2700鈥?/a>


Controlling Nuisance: Blackbirds in Roosts


University of Missouri Extension


Missouri Department of Conservation


U.S. Fish and Wildlife Service


http://extension.missouri.edu/explore/mi鈥?/a>


Below is a page of URLS


http://www.google.com/search?hl=en%26amp;q=how鈥?/a>Does anyone know how to get rid of hundreds of blackbirds that roost in evergreen trees and leave droppings?
If the pie tins don't work. Try fire crackers. That should scare them off.
Try hanging pie tins in the trees.