Acadian Flycatcher

Empidonax virescens

Visually inconspicuous, these flycatchers are found in rich, multi-layered forest interiors where they feed and nest in the understory. They are especially associated with bottomland forests, swamps and damp ravines, and are found on rare occasions in relatively dry, upland forests (Peterjohn and Rice 1991).

Code Frequency

Acadian Flycatchers are best detected by their explosive, often repeated "peet-suh" call, which can carry for some distance through the forest. Their call is also their best identifier, as Acadian Flycatchers can be difficult to distinguish visually from other summer resident flycatchers. Evidence of breeding beyond simple detection in breeding habitat during the breeding season was apparently difficult to obtain for this forest-dwelling species. They likely nested in many blocks where they were recorded as possible breeders. However, in blocks with more fragmented habitat, Atlasers may have recorded unmated, singing males.

Distribution

Acadian Flycatchers were generally distributed statewide although they were recorded in relatively few blocks in the northern one-third of the state. Blocks where this species was recorded seemed strongly related to forest size. Their scattered, sparse occurrence in northern Missouri likely resulted from the fragmented character of forests in that region. Most occurrences in the north were probably associated with bottomland forests such as along the Grand and Chariton rivers. A nest with Eggs: located in Daviess County indicates that breeding might have been confirmed in many northern Missouri blocks with additional Atlaser effort. The small forest tracts of the Mississippi Lowlands apparently provided at least some habitat for the species, especially along the Mississippi River. Probable breeding was recorded in the larger forests of that natural division, at Donaldson Point Conservation Area and Big Oak Tree State Park.

Average Number of Birds / 100 stops

Abundance

Acadian Flycatcher abundance was greatest in the Ozark and Ozark Border natural divisions. The diminishing abundance of Acadians northward across Missouri was expected based on habitat availability and the fact that Iowa marks the northern edge of their range (Dinsmore et al. 1984).

Phenology

The early observation of a nest containing young indicated an early breeding season. In the latter half of the nesting season, nest construction was observed on June 20 and a bird on a nest July 19. Ehrlich et al. (1988) suggested that Acadian Flycatchers have two broods per season whereas Harrison (1975) suggested only one. Considering the length of the breeding season detected during the Atlas Project, two broods are likely in Missouri.

Notes

Although Acadian Flycatchers are occasionally victimized by Brown-headed Cowbirds (Ehrlich et al.1988), no such evidence was recorded during the Atlas Project.

Breeding Evidence

Reported in 368 (30.5%) of 1,207 blocks