I returned to the nest area in the early afternoon, in fact at 1.35.
I quickly got myself concealed and began to wait, just 2 minutes as it happened. Both birds flew in to the boulders in front of the nest and just beneath me. It was exciting when they flew in and the impression that I got from them was that they were excited as well. There was much calling and bobbing up and down. I stayed motionless because I didn't want to betray my presence or upset them in any way. One of the birds had a beak full of nesting material including a dead leaf. This bird quickly flew up in to the nest and as it entered, made a new noise that I haven't heard before. A cross between a call and a chirp. I started to count to see if I could estimate how long this bird, which I thought at the time, was the female, was inside the nest. In the meantime the other bird remained on the boulder beneath, seemingly keeping watch. Later when I had a close look at the images taken of this bird, I noticed that there were remains of some fibres in the beak. On second thoughts, perhaps this was the female and the male was in the nest finishing off by lining the nest with oak leaves. I have read that this is the usual pattern of events. The bird outside the nest flew off after a while and the other bird, after about two minutes, emerged, and then quietly moved away, hopping from rock to rock before disappearing out of view. What happened then perplexed me to say the least. I am pretty sure that the birds were not aware of me whatsoever, but they never returned to the nest while I was there for the next 2 hours, and a bit more. In the meantime I saw them display flying and then they both flew past me and up river. While they were away, I checked the nest to see if an egg had been laid. The nest was wet inside from the parent bird but there was no egg yet. My assessment is that the nest is all but complete and there is no more building to be done. The birds were away feeding in another part of the territory. I have no way of knowing if this is normal behaviour or not.