You really need to figure out what kind of bird you're talking about,
and why it finds your roof so interesting. If it's a grackle or a
starling, you can download some sounds of hawks and play those when
the bird gets near. A twenty dollar owl replica also can dissuade
them for a while. These are only permanent if the bird doesn't have a
vested interest in returning, as they will eventually learn to ignore
the owl or hawk sounds, and come back if there's a good reason.