Circle, are all tundra in which the permafrost dominates soils and vegetation. The monument is in a permafrost region. In the lowland areas the land is shaped by thermokarst forces. Typical thermokarst features seen in the monument include pingos, polygon ice wedges and thaw ponds. Low vegetation covers the land, mainly in tussocks of cottongrass, with shrubby growth of willow, Labrador tea, dwarf birch, mountain alder and other species in moist tundra areas. Wetter areas in the southern part of the monument feature grasses and sedges. Upland regions are Arctic tundra, with lichen, saxifrage, willow and heather. Few trees grow, and the white spruce that do grow are confined to the southeastern corner of the monument. The coastal region supports a variety of large terrestrial and marine mammals. The abundant caribou are part of the West. Large predators include brown bears and wolf packs. Smaller mammals include snowshoe and Arctic hares, weasels, minks, otters, porcupines and a few wolverines. Marine mammals in or near monument waters include fin, bowhead, gray and beluga whales. Seal species include ringed, spotted, bearded and ribbon seals, with occasional walruses. Ringed seals are hunted by native subsistence hunters, and occasionally beluga whales and walrus are hunted as well. Fish species include five species of salmon, burbot, several species of whitefish, Arctic char, Dolly Varden trout, herring and northern pike. Water birds of all kinds nest in the monument. Nesting species include tundra swan, mallard, green-winged teal, common eider, Canada goose, and horned and red-necked grebes. Sandhill cranes also nest on the tundra, with common, Arctic and yellow-billed loons. Seabirds include glaucous gulls, Arctic terns, long-tailed jaegers and common murres. Landbirds include willow and rock ptarmigans. Predatory landbirds include peregrine falcons, snowy owls and goshawks. Endangered species at Cape Krusenstern include the possibly extinct Eskimo curlew, and threatened spectacled eider and Steller's eider. Weather in the coastal monument is subject to extremes. Average low temperatures in January are , and can reach nighttime lows of . Summer temperatures average around , and can reach . Since the park is above the Arctic Circle, the sun does not set from June 3 to July 9, and the sun is visible for only hours on the winter solstice, with long periods of twilight on either side of sunrise and sunset. As is the case over all of northern Alaska, the aurora borealis is often visible on winter nights