The field was formed from wind-blown deposits about 10,000 years ago. It is one of two active dune fields in Alaska. Spring flood waters of the Koyukuk River carry away signs of the past season and recharge the lowlands. The floodplain provides ideal nesting habitat for ducks, geese, and other water-adapted birds. By September more than 400,000 ducks and geese migrate from the refuge to southern wintering grounds.
Black bear are abundant in forests and grizzly bear inhabit the open tundra.
Furbearers on Koyukuk include otter, lynx, beaver, marten, muskrat, and mink. Wolves and moose are common. Other large mammals on the refuge include caribou from the western arctic herd that often winter on portions of the refuge. Work Outdoors at GORP Jobs Click Here. All rights reserved.