Here she had returned to her favoured boulder and was about to fly up and in. It is of real interest to see how clean this boulder is. The presence of Dippers can be detected by looking for "bird-lime" on the tops of exposed rocks and almost all of the rocks and boulders around and about are spotted in this way,,,, with the exception of this boulder and the one next to it. It is obviously a defensive strategy to keep the area clean and clear of any hint at their presence.