First three photos from 15 Sept, last two from 17 Sept. Male first seen at about 11.30, and female emerged from the hollow a short time later. I left after she went back in. When I returned at about 1 pm, he was still sitting there looking very bored and she wasn't visible, presumably still/again inside the hollow. Two days later they were both seen at and in the hollow. (A pair had flown away from this area a month earlier as I approached.)