Tetlin National Wildlife Refuge is a dynamic landscape made up of forests, wetlands, tundra, lakes, mountains and glacial rivers bounded by the snowy peaks of the Alaska Range. This upper Tanana River valley has been called the "Tetlin Passage," because it serves as a major migratory route for birds traveling to and from Canada, the lower 48 and both Central and South America. Many of these birds breed and nest on the refuge. Others pass through on their way to breeding and nesting grounds elsewhere in the state. Migrants, including ducks, geese, swans, cranes, raptors and songbirds, begin arriving in the valley in April, and continue into early June. An estimated 117 species breed on Tetlin during the short summer, when long days and warm temperatures accelerate the growth of plants, insects and other invertebrates, providing a ready source of rich foods for nesting birds.

Tetlin Refuge also supports a variety of large mammals. Dall sheep dot the higher slopes while moose feed upon the tender new growth that springs up in the wake of frequent lightning caused fires. Wolves, grizzly and black bears and members of three different caribou herds range over the refuge.

Two of the six known humpback whitefish spawning areas in the Yukon River drainage are located within the refuge. Along with caribou and moose, these fish are important subsistence resources for area residents. Arctic grayling, northern pike and burbot are also found in the refuge's many streams and lakes.

Abundant wetlands, forests and glacial rivers dominate the landscape of Tetlin National Wildlife Refuge. Most of the Refuge is rolling lowlands, but the Mentasta Mountains in the southwest corner give rise to glacial peaks reaching 8,000 feet.

Until the late 1800's, the indigenous Athabascan people of the Upper Tanana valley roamed the boreal forest in small bands isolated from the outside world. They followed the seasonal migrations of caribou, waterfowl and fish, gathered berries, trapped and hunted small mammals and game birds. Russian explorers entered the Copper River drainage, but failed to gain access to the Upper Tanana. The first explorer to enter the upper Tanana River valley was Lt. Allen, US Army, in 1885. Most of the early contacts made by the Upper Tanana Athabascans were made with traders on the Yukon River.