I had a breeding pair of peregrine falcons living over my porch and there are also many crows that live nearby. One day the falcons had caught and partially eaten a crow who managed to escape the nest and make it to the ground. Every single crow within at least a mile radius (probably close to a hundred) showed up and some of them tried to fight with the falcons. They were loud and quite agitated for a couple of hours. For the rest of the time while the falcons were nesting I stopped feeding the crows peanuts because they steered clear of the area, as soon as the falcons left they showed up again.
I once watched a murder of crows chase down a falcon. I never knew they could fly so aerobatically. They were flying faster than I'd ever seen a crow fly, and maneuvering in ways that I didn't think possible.
Now, when ever I hear crows going absolutely mad, I assume a bird of prey is near by, and almost aways, if you go out and look, you'll see the predator nearby.
Falcons and hawks tend to get out of Dodge really fast when 3-4 crows set their sights on them. They are out for an easy meal, and when confronted with opposition, they do their best to find a new location.
My beagle pays close attention to crows around my home. If a fox is making his rounds, the crows start yelling, and my beagle starts looking out for the fox. (And me too)
Crows are amazing creatures.