I suspect that this is a juvenile of the other Koels I've seen. A year or so ago an ANU student did a study on Koels and Red Wattle birds in the ACT, determining that the wattle bird eggs most resembled the Koel eggs. While I have seen photos of magpie larks and other smaller birds feeding Koel chicks, this sighting seems most related to the ACT study. As I watched a wattle bird landed on a nearby branch and this 'chick' turned and opened its beak as if to be fed. The wattle bird in fact had no food and soon flew off again.