Described as the 'Gateway to the Northern Isles', Yell is the second largest of the Shetland Islands, lying to the northeast of the Shetland Mainland. Shaped like a rectangle that is almost cut in half by two voes (Whale Firth and Mid Yell), it comprises 21211 ha (52412 acres) of lochan-studded blanket peat, mire and croftland with a rocky indented coastline. In summer the moorland is alive with breeding birds such as whimbrel, golden plover, dunlin, eider duck, Arctic skua, Great skua, red-breasted merganser, red-throated divers and merlin, Britain's smallest bird of prey. Many of these birds can be seen on the Lumbister Reserve which extends over an expanse of moorland that includes the Lochs of Lumbister. Yell is also one of the best places in Europe to see otters which thrive on the rich food supplied in the offshore shallows. Yell's highest hill is the Ward of Otterswick which rises to 205m (672 feet). Mid Yell is the island's main settlement and, save for West Sandwick, the majority of the island's hamlets and crofts are to be found on the east coast. These include Gloup, Cullivoe, Sellafirth, Aywick and Burravoe. Early prehistoric remains can be found scattered round the island's coast, including the ancient settlement at Birrier and the Iron-Age broch at Ness of Burraness which is one of 12 broch sites on Yell. Historic buildings include the Old Haa of Burravoe (1637), the haunted Windhouse, the ruined whale station at Grimister and the Kirk of Ness which has been deserted since 1750. At the head of Gloup Voe in the far north stands the Fishermen's Memorial which commemorates the 58 fishermen who were drowned on 21st July 1881. The island's population has fallen from 2611 in 1841 to 1155 in 1961, with a steady decline continuing 1143 (1971), 1191 (1981), 1075 (1991) to 957 in 2001, stabilising at 966 (2011). There are car ferries linking Toft on North Mainland with Ulsta at the south end of the island, and Gutcher in the northeast with Belmont on Unst and Hamarsness on Fetlar.