The St Kilda field mouse (Apodemus sylvaticus hirtensis) is a subspecies of the wood mouse that is endemic to the Scottish archipelago of St Kilda, the island west of Benbecula in the Outer Hebrides, and from mainland Scotland. Unique to the islands, the mouse is believed to have arrived on the boats of Viking settlers more than a millennium ago. It is not to be confused with the St Kilda house mouse (Mus musculus muralis), a subspecies of the house mouse which is now extinct.
