Short answers, pulled from the story.
The first sheep brought to Europe by early farmers were short-tailed animals that appeared during the Neolithic Age as small, double-coated creatures with naturally moulting brown fleece. These breeds possessed characteristic short fluke-shaped tails containing 13 vertebrae compared to over 20 for other sheep.
By the Iron Age these original breeds had been replaced throughout northern and western Europe by somewhat larger sheep imported later from southern Europe. By the early twentieth century short-tailed sheep were restricted to very remote islands and mountains where they persisted in Scandinavia, Ireland, Cornwall, and the Highlands of Scotland.
Most types are very hardy and agile animals adapted to eating rough vegetation in wet and cool climates while displaying a strong preference for browsing trees and shrubs instead of grazing shorter vegetation. The North Ronaldsay breed survives by living largely on seaweed outside a wall surrounding the island just above the high tide mark.
The Kerry Mountain population came from the south-west of Ireland and became extinct in the early twentieth century while the Lítla Dímun lived feral on the island of Lítla Dímun in the Faroe Islands until extinction occurred in the mid-nineteenth century. The Cladagh population survived longest in the Aran Islands before disappearing completely with only a few individuals remaining in existence in the early 1970s.
More than thirty of these breeds survive today across Northern Europe including the Åland archipelago forming part of Finland, the Faroe Islands, Finland, the Shetland archipelago off the north coast of Scotland, and the island of Ouessant off the coast of Brittany France. Some populations like the Boreray breed now live only on the island of Boreray but formerly inhabited the larger island of Hirta.