 Caribou from the migratory Western Arctic Herd, which numbers more than 450,000, often move into the northernmost reaches of the refuge in winter months in search of lichens that lie beneath the snow.The Koyukuk also supports a resident non-migratory caribou population, the Galena Mountain Herd, which numbers about 300.Wolf packs, Canadian lynx and other furbearers, as well as black and grizzly bears, are found on the refuge year around.