Hawks do sometimes form large flocks. They're usually taking advantage of rising thermal air currents, and you may see dozens (and, during migration, up to thousands) soaring together in the right conditions.
I often see flocks of raptors circulating overhead . They can circle for long periods of time without moving their wings . They are much too high for me to determine color or even wing shape. Do any raptors besides black vultures flock in the southern states? I live in NW Arkansas