I think I have observed Baldy and partner mating! I had to fend off a swooping magpie with one hand while taking photos with the other. When I arrived just before midday, Mrs Baldy was sitting at Hollow 2 and Baldy was in the leafy part of the tree a bit higher up. She gave a short half-hearted growl into the hollow at one point (photo 2). She then moved around a bit before joining Baldy. They groomed each other for a couple of minutes and then he mounted her and they remained in that position for about a minute. It was all very sedate with no noise and very little movement. When they separated, Baldy flew to Hollow 2 where he sat quietly and she stayed in place.
John visited the site in the afternoon. Both partners were sitting at Hollow 2. (A SCC was perched on Hollow 3 and left soon after.) Baldy appeared to be sitting with his tail inside the hollow and his body out. They engaged in some 'energetic cuddling' and she occasionally poked her head into the hole. After about 20 minutes they gave their leaving call and flew off to the north.
Thanks Cath - i also observed mating on Thursday by the couple who I think raised chicks in Katies hollow on the Federal Golf Course. I think we have observed mating on about ten occasions and all have been in teh close vicinity of hollows.