The Nunivak Wilderness now contains a total of 600,000 acres and is managed by the Fish & Wildlife Service's a Yukon Delta National Wildlife Refuge . All of the Wilderness is in the state of Alaska. In 1980 the Nunivak Wilderness became part of the now over 110 million acre National Wilderness Preservation System. Off the coast of the delta formed by the Yukon and Kuskokwim Rivers lies 1.1-million-acre Nunivak Island, managed as part of the 20-million-acre Yukon Delta National Wildlife Refuge. Nunivak's southern half has been designated Wilderness. Lava flows and craters found in the interior of the island, some of which hold deep lakes, attest to its volcanic origin. An extensive upland plateau stands 500 to 800 feet above sea level and supports a large herd of reindeer. Introduced in 1920, the herd now numbers over 4,000 individuals. The Eskimos of the village of Mekoryuk, the only community on the island, own and manage the reindeer. More than 40 rivers combine to drain the upland. Tundra, which dominates the landscape, gives way to rocky shores and saltwater lagoons filled with eelgrass (feed for migratory waterfowl) and backed by sand dunes. Isolated low mountains and buttes break the tundra. Vast seabird colonies nest on cliffs along the shoreline, and a large variety of migratory birds flock here in season. Sea mammals frequent the coastal region. Nunivak Island is probably best known for its herd of great shaggy musk oxen. While the Alaskan musk ox became extinct around 1865, these were introduced here from Greenland in 1935. The herd flourished, growing to more than 750 members, and some were shipped to other regions of Alaska. Each year, a permit system determines which hunters will get to shoot a few of the musk oxen, the chance of a lifetime for many.