What environmental factor unifies the Harris's Hawk's vast geographic separation?
Answer
Association with dry, open, or semi-open country
The key unifying factor across its range is its selection of dry, open, or semi-open country, specifically arid and semi-arid regions, deserts, scrublands, and grasslands.

Related Questions
What is the general geographic spread of the Harris's Hawk?What environmental factor unifies the Harris's Hawk's vast geographic separation?What specific US states host established northern populations of the Harris's Hawk?Why are open sightlines essential for the Harris's Hawk's survival strategy?How does the Harris's Hawk's distribution in the US compare to that of the Red-tailed Hawk?What distinguishes the Harris's Hawk's hunting style from many other birds of prey?In cooperative hunting, what is the role of one hawk relative to the prey?Why are Harris's Hawks highly valued in the practice of raptor training (falconry)?According to some ornithological accounts, where does the southern distribution of the Harris's Hawk terminate in South America?What happens to the Harris's Hawk's cooperative tactics if the scrub cover becomes too dense?