When I first arrived at the nest site today one of the birds was just in front of the nest site and moved off when it caught sight of me. Because at first, I only caught sight of one bird, I imagined that the other was perhaps sitting on eggs? But no, after just a few seconds, there was the female doing the usual walk up to the nest and the male was keeping watch, as usual on a nearby boulder in mid-stream. The female entered the nest and after a while they left and I managed to take a quick look in the nest. Still no eggs but even more interesting was the absence of the leaves that I had seen the bird carrying just before and lots of other times previously. I was intrigued, I searched around and there it was staring me in the face.......... another nest. It seems that the nest I found before is an old nest and they are now building another hidden behind this one. Not sure what is going on but it's going to interesting to see how this develops.