Most birds of prey are solitary hunters. Not Harris's Hawks.
Harris's Hawks hunt in packs of two to six, using a few different strategies that allow them to take down bigger prey than they'd otherwise be able to handle.
Via their Wikipedia page:
In one hunting technique, a small group flies ahead and scouts, then another group member flies ahead and scouts, and this continues until the prey is bagged and shared. In another, all the hawks spread around the prey and one bird flushes it out.
The video below shows the Harris's Hawks using the second method described above.
Let's hope Harris's Hawks don't get whatever the birds in The Birds had. That could be bad.