Swamp Ecosystem-Acadian Flycatcher

Acadian Flycatcher

Order: Passeriformes

Family: Tyrannidae

Genus: Empidonax

Species: E. virescens

General Characteristics: A denizen of mature deciduous forests and streamsides, the Acadian Flycatcher is usually first noticed by its explosive "peet-sah" call. It is the largest and greenest of the North American Empidonax. The Empidonax flycatchers are very difficult to tell apart. The safest way to differentiate them is by habitat, range, and voice in the breeding season. Differences in plumage due to molt, wear and age make the plumage quite variable. A combination of features is helpful for identifying this species: size-it is larger than Yellow-bellied and Least, color-it has greener upperparts and yellower underparts than all but the Yellow-bellied. The Yellow-bellied flycatcher is usually more yellow underneath-especially on the throat, is smaller and more active, and has a smaller bill. Alder and Willow are browner above and whiter below with less obvious eye rings. Least is smaller, grayer above and whiter below and has a smaller bill. Empidonax flycatchers from the western United States have darker lower mandibles, and whiter underparts (Gray and Dusky), darker breasts (Hammond's), or oval eye rings (Pacific Slope and Cordilleran) as well as different ranges. Pewees are larger, browner above, whiter below and have indistinct eye rings.

Special Adaptations: The Acadian Flycatcher is a common host to the brood-parasitic Brown-headed Cowbird, which lays its eggs in other birds' nests. Nests are parasitized more in small woodlots than in large tracts of forest. The frequency of parasitism is lower for the flycatcher than for other bird species in the same forests. From the cowbird's perspective the Acadian Flycatcher does not seem to be a particularly good host: only 16% of cowbird young in Acadian Flycatcher nests fledged successfully.