Habitats consist of rivers and streams, seasonal and permanent wetlands, forested wetlands, riparian areas, grasslands, shrublands, and forested uplands. When flooded in fall and winter it provides resting and wintering habitat for ducks, Canada geese, tundra swan, and a variety of other waterbirds. Dominant ducks consist of northern pintail, mallard, and wigeon. Canada geese include dusky and cackling subspecies. Tualatin River Refuge supports significant breeding populations of wood duck and hooded mergansers and to a lesser extent cinnamon teal, mallard, and resident Canada geese. It is a significant breeding area for neotropical migratory birds as well. Threatened, endangered, and candidate species for federal listing which frequent the area include peregrine falcon, bald eagle, Aleutian Canada goose, western pond turtle, and the northern red-legged frog.