I literally turned on my NatureMapr App to record an unusual Frog call. Before a double take, and I realized that the incessant creaking was a begging juvenile GG. Its parents were resting up nearby in the middle of the afternoon. Photo 5 was a suitable hollow within 20m of where they were perched. They certainly could be passing through area as well.
Thanks Richard, dimension wise does look like a suitable hollow. However we don't know how far Gang-gangs travel post fledging, but we do know that fledglings can still be fed 9 months after leaving the nest. Newly fledged birds can sometimes be recognised because they have bright white beaks, which fad within a matter of days when exposed to the sun. Yours lack such a beak colour and may have travelled some distance from their nest.