The 160,000 strong Porcupine Caribou Herd calves near Barter Island. The northern portion of the refuge receives only about 6 inches of precipitation annually. Snow cover usually is completely gone by early to mid-June, but starts accumulating again in early September. Snowfall and freezing temperatures may occur during any month. They are frequently sighted near Barter Island especially during whaling season.
Black bears live on the south side of the refuge.
Five wolf packs totaling approximately 30 individuals live on the northern portion of the refuge. Moose use the north side river drainages and a variety of habitats on the south side of the refuge. Wolverines, or Qavvik, occur on the refuge, but they are rare. Dall Sheep also live on the refuge. Their habitat is in the Brooks Range.