Great Black Hawk soars frequently on wings held flat, but also regularly perch-hunts near water, often from low perches. Usually is seen singly or in pairs.

There is very little information on territoriality, or territory or home range size, for Great Black Hawk. Thiollay (1989) estimated the density of Great Black Hawk in one region of French Guiana as one pair/ha, but five or fewer pairs/4200 ha, and an overall estimated density of 17 pairs/10,000 ha (100 km²).

There is little detailed information on sexual behavior in Great Black Hawk. In a display flight, soars in circles while calling and dangling the tarsi (Howell and Webb 1995). Great Black Hawk is socially monogamous.

Great Black Hawk usually is solitary or in pairs.

No reports of predation on Great Black Hawk.