I am NOT advocating shooting crows; they are a wonderful "alarm" system. With that said, last spring I saw a family of crows harassing a mother robin on her nest; when they finally got her off the nest one of the other crows swooped down and snagged a baby, then a few others did the same thing. These were very young, baby birds, but crows are omnivores and will eat mice, frogs, small snakes. lizards... and small birds.