Rüppell's vulture (Gyps rueppelli) sitting on the roof of the former rhinoceros house, currently a part of the savanna aviary and used as bird housing.
Antwerp Zoo has Rüppell's vultures in the vulture/marabou/waldrapp aviary next to the hippopotamus house. Whether this bird didn't get along there or this bird was placed in the savanna aviary to again attempt to add a vulture to the already rich bird collection of this aviary (after this experiment failed with a hooded vulture due to agression towards the public) I do not know. There was no sign for this species yet in the aviary.
According to a member at the Laafsekikkers zoo forum, two of Antwerp Zoo's four Rüppell's vultures were placed in the savanna aviary to help filling it up. They appear to be doing well with the other birds and the visitors, unlike the hooded vulture Freddy who made a nuissance of himself in the savanna aviary and has been moved elsewhere.