There are forests of white spruce and paper birch on the hills overlooking the Yukon and Kuskokwim Rivers. Alpine meadow vegetation is predominant at higher elevations. There are low to moderate populations of brown bears. River otters are found throughout major river drainages. Northern bog lemmings populate wet alpine and subalpine meadows.
Alpine tundra provides habitat for horned larks, surfbirds, and white-tailed ptarmigan.
Sharp-shinned hawks and golden eagles are common avian predators.