Back at the nest site this evening there was quite a change in behaviour and now I am not really sure what is happening. Firstly, for the first hour of my observations I didn't see any activity at the nest burrow at all. From time to time I heard a bird but there was quite a lot of activity from people walking on the bank enjoying the warm early summer sunshine and it meant that the birds were keeping away until the coast was clear. Thats the way it proved because within a few minutes of quiet resuming I heard, then saw a bird which flew in to the willow trees next to the hide. This time it was perched on a better perch and I managed to improve on the photograph taken this morning.
The male became very active and was flying up and down the river. Every few minutes he would be back again and I assumed he was calling to the female who I was sure was in the nest burrow, At one point the male flew up in to the burrow and then I saw a bird fly up stream but I hadn't seen one leave the nest. The activity continued with much calling and "tooing and frowing" Every time I had the chance to check which bird it was, it was always the male. I was just about to leave for home and had started to pack up the kit but I was still inside the hide when the male landed on the same perch as before but this time with a small wriggling fish in it's beak. He left the perch and flew to the left but I could still hear him, now even more noisy and excited and I heard a different call which was more intense and had an element of a throaty chirp along with the usual high pitch one. I managed to catch sight of him and then to my surprise, there was the female as well. They were both tucked under cover and I couldn't see for certain but I am quite sure that the male fed the fish to the female. I don't know if the female had been there all along or if she had just flown over to interact with the male. I suspect that if there was a problem and they had decided that the burrow was no longer suitable then they would have left the area. I think the fact that I saw a bird enter the burrow and then saw both birds opposite the nest means that this nest burrow is in use. I am not sure if eggs have been laid yet though.