@jayjds2 Unfortunately I didn't see them there on my last visit to Houston Zoo, but I can ask someone I know that works there or even email the zoo's bird department directly. Have you done that yet?
Also, what is the story with Louisville Zoo's Hawaiian hawk and how did they source this animal?
I went to Houston in December, and asked the bird department about other species but not this one. Houston’s bird collection is actually declining and they’ve gone out of a lot of their cooler species, unfortunately. Not sure about Hawaiian hawks, haven’t made a further attempt to contact them. I also don’t know the story of Louisville’s individual.