English: Wood Mouse (Apodemus sylvaticus), Baltasound, Shetland Islands, Great Britain. Wood Mouse is not a very appropriate name for Shetland, where there are no woods, so it is more appropriately known as the "Hill Mouse" or "Field Mouse" in Shetland. Like all terrestrial mammals in Shetland, mice were brought to the islands by humans; in this case accidentally. It was once thought that mice arrived in Shetland with the Vikings, but it is now known from archaeology that they were here long before this. Shetland Field Mice are larger and darker than mice found in the rest of Britain or on mainland Europe and they breed on all islands inhabited by humans. The named subspecies are A. s. granti described from Yell, A. s. thuleo from Foula and A. s. friadriensis from Fair Isle. The races found elsewhere in Shetland are unknown – it is likely that the Yell race breeds elsewhere but it is possible that new races are awaiting description on other islands.