Callocephalon fimbriatum

I have seen Gang-Gangs enter this hollow on several occassions but when poled on 20/12/21 the hollow was empty except for chewed bark. Prior to poling on teh 20th I didn’t see any birds emerge from the hollow, but a male and female were in the branches above the hollow. At about 6:10 a pair appeared on top of a nearby dead tree above a hollow. The Yellow Box pair flew over and squawked at and pecked the dead tree pair. They continued to aggressively interact till about 6:25 when the Yellow Box pair flew over to a Eucalyptus cineria, and began to eat the gum nuts. There was a short break in the interaction at about 6;20 when another pair flying in a south-north direction landed in a tree adjacent to the Yellow Box and the Yellow Box pair noisily shooed them on before returning to take on the dead tree pair. Once the Yellow Box pair took off to the Eucalyptus cinerea, the dead tree pair flew to an adjacent casuarina (but did not eat) and then flew off the the south. The yellow Box pair then flew back to the yellow box but returned a minute later to Blue Gums on the western boundary of the course. They started calling down and spreading wings above a hollow in a Blue Gum in which I had previously observed a pair of nesting Sulphur Crested Cockatoos. At about 6:40 a pair of Sulphur Crested Cockatoos arrived and drove the Gang-gangs away from the hollow. Both the Gang-gang and Sulphur Crested Cockatoo pairs remained quietly nearby for about a minute until the Yellow Box Gang-Gang pair flew off towards the west joining another Gang-gang pair that were flying overhead and calling, flying in an east-west direction. Tree reported separately at https://canberra.naturemapr.org/sightings/4241579