What the heck?

Last night at around dusk I was letting Corky out the back patio door.  He went out and I happened to look next door and saw a big bird.  I hurried up and told my husband to come look.  By the time I turned around to look again the bird had already taken off.  He flew really fast over our garage and through the trees. 

I've never seen a bird like this.  It was not the usual variety of birds we see around here.  It was a pretty big bird.  My husband thinks it might have been a falcon or a hawk.  It all happened so fast and because it was starting to get dark I really couldn't tell the colors on the bird.

I'll have to keep my eyes open from now on before I let Corky out in case it ever comes back.