Fair Isle Wren 110923 Troglodytes troglodytes fridariensis
This is one of the most restricted sub-species of Wren as there are only about 37 breeding pairs on the island. There are minor differences in plumage and measurements but the main difference is in habitat preference - they normally feed on rocky shores and rarely venture into the centre of the island. The breeding territories are all along the shore and it does not breed away from them.
None of these birds responded to a recording of the nominate sub-species, they seemed interested but did not sing back.