Quite entertaining. The parent birds were out first, singing in the tree tops to the morning light. Then they made some odd calls, and two youngsters popped out of the hollow and they fed them and had them follow round and round the tree. Then one parent bird returned and hunted out the rest - two or three very underdone youngsters, whom they didn't feed at the hollow but forced them up and chase them and then be rewarded. The smallest one was back in the nest in no time, with parent bird blessing.