I watched the nest yesterday for a couple of hours in the afternoon. It's now 14 days since egg laying began and incubation has thrown up a few interesting facts. To start with, the female, who does all the incubation has now developed the habit of leaving the nest to feed every 30 minutes or so. As I have said before, she is away from the nest for just 8 minutes, literally to the second. The male is not always aware that she has departed and yesterday I watched him arrive with a healthy beak full of adult Mayflies. This is the first time that I have seen the male, or female for that matter, feeding on adult Mayfly and my guess would be that the entire breeding cycle has been timed perfectly so that when there are chicks in the nest there is going to be a proliferation of Mayfly. He called to the female from a boulder close to the nest but didn't get any response because she was away feeding. He continued calling her but didn't fly up to her with the flies. I made the assumption that had she been in the nest she would have responded and he would have delivered the insects. I am certain that this is the case but I haven't heard her calling from the nest. before and it was interesting to realise that he was waiting for a response from her. Eventually after flying from boulder to boulder in front of the nest, he decided to eat the food himself but not before he had spent at least 5 minutes calling her. To think that the arrival of chicks in the nest has been timed to coincide with the Mayfly hatch is a stunning fact. Quite how that has been judged is a mysterious wonder to me.