What is a good way to keep pigeons away--from roof and gutters?

Answer 1

A friend put rubber snakes on his roof to keep the birds off. It works for a while, but you have to move them occasionally so that the birds don't get used to them.
Also there are cat, owl and hawk silhouette's commercially available which are supposed to do the same thing. Some move with wind to give them a more realistic look.

Answer 2

They sell fake plastic Owls.to put on the roof