Clouds of ducks, cranes, and geese, reminiscent of pre-European accounts, migrate through the Refuge. Thousands of northern pintails, sandhill cranes, and Canada geese can be seen throughout the valley resting and refueling for their trek to northern breeding grounds.
Typically, the river is one of the first major areas of water to open up within the valley, attracting large numbers of waterfowl. Large concentrations of bald eagles roost along the river during this time to feed on the arriving waterfowl as well as on the numerous winter killed fish found along the banks. As migration progresses, a variety of songbird species use the riparian corridor.