@Sarus Crane From what I can remember, probably somewhere in the range of 3 to 4 feet. It was quite impressive just how big this bird is (and even more so if you think it can fly). I have seen living specimens at Duisburg and Pairi Daiza years ago and they are they definitely even more impressive alive.
@KevinB I was at the National Zoo a few years back and I wasn't able to see the Koris there at ground level because their exhibit is like two feet below you. Does Duisberg and Pairi Daiza keep theirs in exhibits at the same level as the visitors?
@Sarus Crane Pairi Daiza kept them in an aviary at visitor level (their last one died in 2017 according to ZooTierListe and the aviary is not there anymore), Duisburg keeps them in a ground-level paddock with Kirk's dik-dik.