The Acadian Flycatcher (Empidonax virescens) is a small, olive-colored flycatcher that breeds in mature, shaded deciduous forests near wetlands. As an inconspicuous interior forest dweller, it is often difficult to see in dense cover; its distinctive song is the most reliable field identification tool.
Learn to identify
Adult Acadian Flycatcher of eastern North America.
Learning lesson · openly licensed photographs, labelled by BirdBot; labels checked against the cited sources and approved by AI
Wide bill: dark above; the lower part is yellowish. White eye-ring: a clear ring around the dark eye. Olive upperparts: darker on the wings and tail; pale below. Two white wing bars: contrast with the darker wing. Most Empidonax look alike; confirm with the explosive peet-sa song.
Fall birds may be very yellow below.
Sources: Audubon Guide to North American Birds: Acadian Flycatcher · Wikipedia: Acadian flycatcher (revision 1381617515)
Photo: Andrew Weitzel from Lancaster, PA, USA, CC BY-SA 2.0, via Wikimedia Commons; labels added by BirdBot.
Adult Acadian Flycatchers are small (13 to 15 cm) with a triangular head. They are olive in color with white and sometimes yellowish flank and belly areas. Key visual identifiers include a distinct, thin, white ring around each eye, typically two white wing bars, a black upper mandible, and a yellow to pink lower mandible. Juveniles are browner than adults, with buff-edged feathers and darker buff wing bars.
This species is frequently confused with other members of the genus Empidonax, including the Alder Flycatcher (Empidonax alnorum), Yellow-bellied Flycatcher (Empidonax flaviventris), Willow Flycatcher (Empidonax traillii), and Least Flycatcher (Empidonax minimus). While visual cues like the white eye-ring and bill color help, the most reliable field identification tool is the bird's voice, habitat, and breeding behavior.
The Acadian Flycatcher's song is a distinctive "peet-sah" or "tee-chup" that serves as a primary identification tool. These songs can vary depending on the time of day. Males are typically more vocal, especially when territorial neighbors are present, while females tend to remain quiet, particularly while on the nest. Both sexes frequently call to each other, and vocalization rates increase when defending nests.
Acadian Flycatchers have specific habitat requirements. They breed in mature, deciduous forests with thick, shaded canopies and open understories, typically situated near wetland habitats such as streams, ravines, or swamps. They are interior forest dwellers, occupying the lowest tree canopy and understory layers. During the non-breeding season, they winter in lowland tropical forests of South America, specifically from Nicaragua to Ecuador and Venezuela.
These birds are very maneuverable flyers, capable of flying backwards. This agility is used for "aerial hawking" (catching insects in flight) and gleaning insects or berries from branches. Notably, Acadian Flycatchers have no known ability to walk or hop. To bathe, they dive into water, striking only their chests before returning to a branch to clean themselves.
They are semi-social during the breeding season, forming pair bonds near other Acadian Flycatchers. Pairs often return to the same nest site in subsequent years. Females typically evacuate the nest when a potential threat is within 23 meters, making them difficult to locate in the field.
Females choose nesting sites and build hammock or cup-like nests 3 to 9 meters above the ground in the forks of horizontal branches. Nests are constructed from plant stems and fibrils, held together with dried grass stems and spider silk. They are often adorned with "nest tails" (hanging plant debris) for concealment. Nests are sometimes built over water in ravine settings to aid in nest defense.
Breeding occurs in the United States between May and August. Females may produce 1 to 2 broods per season, with each brood yielding 2 to 4 eggs. Incubation lasts 13 to 14 days, and both parents care for the young until they fledge (13 to 15 days after hatching) and for another 12 days after fledging. If the female begins incubating a second clutch, the male solely cares for the first brood.
Acadian Flycatchers are mainly insectivores. Their diet consists of mosquitoes, flies, insect larvae, small moths, flying ants, small beetles, and some spiders. They occasionally eat fruits such as blackberries and raspberries. Juveniles are fed diets consisting almost entirely of insects.
The Acadian Flycatcher is listed as Least Concern (LC) in the AviList v2026 dataset. While populations have declined in specific areas such as Minnesota, Wisconsin, and southeastern Canada, the species remains abundant in most of its North American breeding range. As an interior forest dweller, it is sensitive to habitat fragmentation and deforestation, particularly in agricultural areas. The species is protected under the Migratory Bird Act.
Because Acadian Flycatchers are inconspicuous and prefer dense, shady forests, listening is the most effective way to find them. Look for mature, shaded deciduous forests near streams or swamps. When you hear the song described in the Voice section, use it to triangulate the bird's position. Watch for a bird that flies backward or hovers in the understory, a behavior notable among common eastern flycatchers. Move slowly and quietly, minimizing your movement to avoid startling the bird. Scan the lower canopy and understory for a small olive bird with a white eye-ring. Maintain a respectful distance, especially during the breeding season, as females will abandon nests if threatened. Avoid disturbing the habitat, as these birds require large, intact forest blocks to thrive.
Historical accounts by Reed (1919) and Blanchan (1923) align with current understanding of the species' preference for shady woods near water and its inconspicuous nature. While early observers noted the bird's similarity to other flycatchers, modern field guides emphasize the white eye-ring and specific vocalizations as primary identification tools.
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