The chase is constantly on for all raptors, gulls, crows, ravens, and vultures, even if these trespassers have no interest in the nest they can not fly over it without a serious confrontation. Once there is any type of chase the screaming begins and doesn't end until the trespasser is long gone. This is the male who just returned from a chase the nest is directly below, the female was on the nest at the time.
The chick eating is approximately 24 hours old and the other chick has recently hatched it doesn't eat for the first 24 hours and prefers to stay in the curled up egg shape. Sorry about the clicking I don't have the option of turning off the volume in my editing program. The voice isn't me it was another photographer.
Bait balls are a great source of food for many species.