Wikipedia:Today's featured article/February 21, 2018

The North Ronaldsay is a breed of domestic sheep from the northernmost island of Orkney, off the north coast of Scotland. It belongs to the Northern European short-tailed sheep group of breeds, and has evolved without much cross-breeding with modern breeds. It is a smaller sheep than most, with the rams (males) horned and ewes (females) mostly hornless. It was formerly kept primarily for wool, but now the two largest flocks are feral, one on North Ronaldsay and another on the Orkney island of Linga Holm. The Rare Breeds Survival Trust lists the breed as "vulnerable", with fewer than 600 registered breeding females in the United Kingdom. The sheep on North Ronaldsay are confined to the shoreline by a 1.8 m tall (6 ft) dry-stone wall, which completely encircles the island. The wall was built originally to protect the shoreline and keep the sheep inside it, but when seaweed farming on the shore became uneconomical, the sheep were banished outside the wall to protect the fields and crofts inside. Because of their restricted environment, the sheep evolved to subsist almost entirely on seaweed.