Watched tree from 6.00am - 7.30. At 6:45 pair arrived from the west and sat on branch above hollow. at 6:50 Male went and bobbed head in and out of hollow. At 6:55 male entered hollow for 30 seconds and then returned to hollow rim. At 6:57 male went back into hollow form just over a minute and then returned again to rim. At 7:00 male entered hollow again for just over 5 minutes. at 7:10 pair flew off to the west.