Eriskay is the breeding area of the Eriskay pony, a special breed that is unique to the Hebrides, very useful for traversing the rough terrain of mountains and the flat machair, as well as being small enough to get onto birlinns, that were used by the Picts as warhorses according to this standing stones (Aberlemno, for example). The island's population varies from five hundred to a thousand, and there is a causeway that links the island to South Uist (the description of this one I have from families originally from Eriskay makes it appear to be a different causeway to the one there at the moment...no big deal, the Lordship of the Isles had paved roads on the major islands, canals on Skye, etc., they probably had causeways as well).