On one of my regular walks I'm always hearing the Wren's singing and this has been the same for many years. Today's walk at low tide seems to have been timed right for getting a good view. Suddenly there were at least 5 wrens darting about at a cave like area of cliff. Would appear to have been two adults and 3 chicks and I'm guessing the out of focus Wren on the left is a chick (by the size of its tail). The nest area was clearly visible although very well hidden.
Shetland has its own particular sub-species of Wren - Troglodytes Troglodytes Zetlandicus.
