I have had hawks in the past kill birds. Currently I see either a Red Tail or Red Shouldered hawk most every day on the same branch in a persimmon tree. Maybe it's after field mice or rats, maybe squirrels. We have Fox Squirrels which don't do any harm but we also have Gray Squirrels that do. I don't mind if the hawks take a Gray squirrel. I've been leaving the birds in their pens where they are safe.