This is a great photo, but I think that this might be a Fischer's Turaco (Turaco fischeri) and not a Hartlaub's Turaco. The Fischer's Turaco has the red-tipped crest and a reddish bill color, while the Hartlaub's Turaco has a wide purple band across the crest and a different bill color (brownish with a tint of pink). Both species have the green neck and throat, purplish wings, and the bands of white feathers below and in front of the eye (the the white band in front of the eye of the Hartlaub's Turaco is thicker and looks more like a white spot). It's likely that both species were in this exhibit.
