The female and male gang gangs were perched high up in the tree away from the hollow, calling, sometimes softly, sometimes insistently (particularly the male), for the nestling to come out. She remained in the hollow, answering back. After half an hour, the female flew in and fed her young - for 20 minutes! Then flew off. The male flew in, fed the baby for a few seconds, then flew off also. For whatever reason, I took a photo of the hollow after both parents had flown off - and only discovered later, when looking at the photos, that there was the head of a female nestling peeking out!