Here is what I've read about the vultures in the Northeast & mid-Atlantic US:
Turkey vultures(with the red heads) are said to eat only carrion(dead creatures) and are easily scared off.
Black vultures(with black heads) are more aggressive and destructive. Once they choose a place to roost, they are hard to get rid of. They have been said to injure newborn animals, as well as their mothers, though I haven't seen this myself. They tore a hole in a toy that I have out in the pasture for my colt.
I had a bad problem with them last year, they would bathe in my horse's troughs, making the water so disgusting that they wouldn't drink. I also didn't like how close they would get to my colt and my old mare. They don't like getting sprayed with water, getting chased, or loud noises. I hope that they leave your birds alone.