Around here we have both turkey and black vultures (the turkey vultures have red faces). The black vultures are known to be more aggressive and are the ones who will go after newborn calves if desperate for food. I've not had any problem with either variety though they both roost about 300 yards away from my house and regularly have flyovers. My chickens generally ignore them which originally concerned me until I realized they can apparently tell the difference between a vulture and a hawk.