American Crow (Corvus brachyrhnchos) are very intelligent birds, having the same brain to body weight ration as humans. They have been known to modify and use tools to get food. Tests indicate they may be self-aware. They are omnivorous and scavenge on dead animals, but will go for live animals also. Because they will take eggs and young of other birds, smaller birds, such as blackbirds may mob them, as in shots below. I’ve also seen one knock a bat out of the sky