This is a beautiful picture! Because it has a dark malar stripe, I believe that this is a White-crowned Robin-Chat (Crossypha albicapillus). The two species are sometimes misidentifed by zoos and bird dealers but C. niveicapilla has an orange malar stripe and an orange collar around the back of the neck. I have misidentified these many times so I've learned to look closely at certain characteristics of the head. Also, albicapillus tends to be larger than niveicapilla. I don't know if the two species hybridize in captivity, but I suppose it's possible. Thanks again for posting all of these great photos of the birds at Vogelpark Avifauna!
@Summer Tanager I checked ZTL again, apparently Avifauna actually keeps both species in their tropical hall and I wasn't sufficiently diligent in checking ZTL or making sure I correctly ID'd the species, for which I apologize. I have now changed the title to the correct species. Thank you for the correction and for your nice comment. There are still quite a few more pictures from Avifauna to come also.
@KevinB There's absolutely no need to apologize! I've mistaken the two species half a dozen times myself! And it's especially difficult when both species are present in a large facility. Thank you again for posting these great photos!