We have bluejays from time to time, and they are indeed bullies about any smaller birds.
We also have pair of Mourning Doves that come regularly and peck at the seeds dropped on the ground by birds who visit our feeders (which the Doves haven't figured out how to use.) The Doves are always very passive and ignore and are ignored by the squirrels.
Then, just the other day, a very aggressive Mourning Dove arrived and chased away the regular visitors and the squirrels. The regulars tried to come back and were again chased away by the newcomer, who acted as if he was hopped up on Opioids.