I could't visit the Dipper site yesterday so consequently I was anxious to check that everything was OK this morning. Both birds were present in front of the nest which is now a classic feat of avian engineering, a ball of moss that would be impossible to see if you didn't know it was there. Some leaves were being carried now, the finishing touches to the nest. Moss is still being brought but when one of the pair is in the nest it's impossible to see the occupant. The birds are still using a favourite boulder to land on both before they enter and when they leave. At one point the female was preening, perched on this boulder, we both heard the male flying down the river, calling as he flew. The female reacted by adopting a low posture as though she was going to be mated, he landed and performed a wing fluttering display and then flew up to the nest.