A lot of people don't like blue jays. They can be aggressive toward smaller birds, and are known to eat the eggs of other birds. They're loud, raucous, in-your-face birds.
But sometimes that's a good thing. Yesterday, we suddenly heard a blue-jay commotion out in the back yard. It sounded like every jay in the neighborhood was right outside our door. Cat? I wondered, as I peered out the kitchen window. No, not a cat -- a HAWK! Sitting in our woodpeckers' favorite tree, big and supremely confident, he surveyed our yard, looking for an easy meal.
All the birds had long since scattered. Not a bird to be seen anywhere, and none to be heard, except for those blue jays. They kept up the alarm until after the hawk had flown off, still hungry (thank goodness).
As for me, since the birds were safe, I made a grab for the camera, but missed him. He came back later in the day, and once again, the yard alarm went off, but I missed him again. It was probably a Cooper's Hawk, as far as I could tell, although there are a few hawks that are similar. Here is one I photographed last year in Illinois.
I would feel terrible if our bird feeders turned into hawk feeders. As far as I'm concerned, the blue jays are very welcome at our place!