Alder flycatchers are apparently most numerous 20 May to 5 June. Departure of this species occurs 15-20 September. Fairly common to locally common nesting species north of the Tension Zone. Within this zone of overlap, observations of breeding pairs have been made in southern Washington and northwestern Pierce counties. Documented nesting records exist for Polk and Douglas counties.
Alder flycatchers use a greater diversity of habitat types than is used by the preceding species.
Nests in Polk County were in Alder Thicket habitat where speckled alder was the predominant shrub species. Elsewhere, breeding pairs have been recorded in Northern Hardwood Forest, Black Spruce-Tamarack Bogs, and Deciduous Clear Cuts. Regular migrant and nesting species. 10 May. Peak abundance occurs 15 May in the Western Upland to 20 May in the north. Fall migration begins in early August.