Vancouver Avian Research Centre

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Species: Willow Flycatcher Empidonax traillii

Description:

The Willow Flycatcher is the most peweelike Empidonax flycatcher.
This species is usually indistinguishable from Alder Flycatcher except by voice. The typical song is a snappy FITZ-bew.
Formerly considered conspecific with the Alder, the 2 together were referred to as Traill’s Flycatcher until 1973, when they were recognized as separate species. Like most members of the genus Empidonax, this flycatcher is difficult to identify in the field without vocal, habitat and geographical reference.
The Willow breeds from Maine to British Columbia and as far south as southern Arizona and southern California. It winters from southern Mexico to northern South America.

Identification:

General: One of the largest Empidonax, with relatively flat forehead and distinct peak on rear crown; long, broad bill; moderate primary projection; and broad, straight-sided tail. 13.3-17.0 cm length. 11.3-16.4 g weight.

Adult Male: White throat contrasts with diffuse, dull olive to brownish breast band; bill wide and moderately long for Empidonax, entirely dull yellow-orange or pinkish on lower mandible and blackish on upper mandible; whitish-gray wing-bars with anterior wing-bars often darker and duller than posterior. Upper parts drab olive, becoming brownish gray with wear; crown often darker. Underparts light gray, washed with yellowish on the belly; indistinct (sometimes lacking), whitish eye-ring.

Adult female: Sexes alike in appearance.

Similar Species: Wood-pewees generally similar in plumage colour and pattern but slightly larger, with longer wings that extend farther down tail, longer primary extension, more notice-ably peaked nape and crest, and different behaviour of habitually returning to prominent perch (more so than Empidonax) and quivering wings but not flicking tail, unlike Willow Flycatcher.

Behavior: The Willow Flycatcher is primarily an aerial forager, capturing most of its insect diet on the wing, but it may hover-glean extensively from leaf surfaces or occasionally take insects from the ground.

Habitat: Found in brushy habitats in wet areas; also in pastures; also edges of mountain meadows. Shrubbery along watercourses and willow covered islands.

Information:

The Willow Flycatcher is a common migratory species and the most widely distributed North American Empidonax. This species was given its name in 1831 by J.J Audubon for his friend Dr. Thomas Stewart Traill of Edinburgh.
The nest is a firm thick-walled cup of plant fibers lined with plant down and cottony fibers, placed in an upright crotch of a shrub 2-6ft high. 3-4, whitish with darker marked eggs.

Conservation Status:

Because the Willow Flycatcher is restricted to river corridors (at least in the arid parts of the West), it is vulnerable to a variety of human activities that may alter or degrade such habitats, activities including river dewatering, channelization, overgrazing, dam construction, and urbanization. Breeding Bird Survey data show this species decreasing in number in the North American continent during the period 1966-1996.
 
Capture Rates


Common in high numbers and a breeding bird at Colony Farm, Willow Flycatchers are present in the park from May through October. Capture rates (2010-2012; standardized as birds captured per 100 net hours) peak however in August corresponding to juvenile dispersal. This flycatcher migrates south for the winter as indicated by zero capture rates from November through April.


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