Where I live, an island right by the mainland, birds of prey are not allowed. If one shows up, the crows will all take to the air, maybe fifty to a hundred of them, and will yell and chase the bird of prey until it leaves the island. Once it is over water, they will give a few last screams and turn around and go back to their business.
I've seen a bird of prey try to dive and swoop low over the land to evade them. They'll follow, some diving down low after it and some at a distance to keep an eye on it, until it's gone.
We basically have a crow air force keeping all the other birds and little mammals safe.
There are many bird species that do the same. Last year in Rotterdam, Netherlands they released a trained American bald eagle from a highrise building to fly to a designated spot across the river. It never arrived there as it was attacked from all sides by other birds, mostly seagulls, and chased across the city. It took hours to find the eagle, and when they did the poor beast was exhausted.
That's strength in numbers. I saw two crows trying this against an eagle,... I think they only survived that because the eagle was too lazy and figured it was easier to just grab some trainer-provided food after the show. Mind, the crows probably didn't recognize the huge bird, since they're not native here. That one "belonged" to a small wildlife reservoir. The trainer said it was more like he agreed to stay there in exchange for free lunch; which meant after a show the bird would occasionally hit the road for a few days, if he felt like it.
Staying still (minimizing visibility through motion detection) and then moving at the last moment is better avoidance strategy for a bird of prey, unless there's an actual hole they can disappear down.
