Those aviaries at Taronga hold some wonderful birds, but you need to wait quietly to see them, and most visitors, regrettably, don't have the patience.
I would estimate that 95% of Taronga's visitors don't even enter that aviary area.
Some years ago I spoke to Graham Phipps, Curator of Birds, who told me that, contrary to popular belief, the small softbilled birds at Taronga are aviary bred, not wild caught. Although most aviculturists are into larger flashier birds like parrots, there is a small group of skilled and enthusiastic birdkeepers who specialise in softbills, keeping and breeding them in large planted aviaries and swapping birds among themselves.