Vancouver Avian Research Centre

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Species: Pacific-Slope Flycatcher Empidonax difficilis

Description:

A small Tyrannid flycatcher that occurs along the coastal regions of western North America from southern Alaska to Baja California.

Identification:

Plumage is a plain olive brown above with yellowish throat and belly. Breast is olive-gray. White eye ring is broad and extended. Lower jaw is bright yellow to orange while upper jaw is dark. Two pale bars on dark wings. Length is up to 14 cm.

Adult Male: Similar to female. Needs to be in hand for sexing unless singing.

Adult Female: Similar to male. Needs to be in hand for sexing.

Juvenile: Plumage duller and grayer than adults. Indistinct wing bars are buffy. Apparent wispiness of head feathers.

Similar Species: Virtually identical to the Cordilleran flycatcher with which it was once lumped together as a single species: Western flycatcher. Male Pacific-Slope flycatchers have a single note to their call while the male Cordilleran has two syllables. Cordillerans are a more inland species with a preference for coniferous forests for breeding habitat. Observers less familiar with the Empidonax flycatchers might confuse the Pacific-slope flycatcher other species in the genus.
Yellow-bellied flycatcher is also similar but it has a shorter tail than the Pacific slope and its wing bars are more yellow and brighter.

Behavior: Like many flycatchers, this passerine sits on inconspicuous branch and hawks for flying insects. Sometimes it will glean prey off leaves. Shallow wing-beats give it a weak fluttering flight.

Habitat: Found in moist deciduous woodlands or mixed forests that provides sufficient shade. Riparian provides best breeding habitat.

Information:

Pacific-Slope flycatchers winter in Mexico and Central America and return to the western US and Canada during the breeding season.
Breeding females tend to build near water in a tree crotch, on cliff ledges and sometimes human structures. They prefer shady areas and the nest will be between 0.3 m to 13 m above ground. Nest is large and bulky consisting of moss, lichen, grass, twigs and lined with finer material such as fur and feathers. She will lay 3-5 eggs and incubate them for 16 days. Hatchlings would fledge in a further 16 days. Sometimes a second brood is reared. First brood fledges in May and the pair may nest again in July. There is a low incidence of brood parasitism by cowbirds.
Coastal birds have been recorded from mid-March until late October. Elsewhere in the BC province it migrates from the area earlier.
It is almost exclusively insectivorous but it has been observed feeding on berries and seeds.
A group of flycatchers are called an “outfield”, “swatting”, “zapper” or “zipper”.

Conservation Status: (Least Concern)

Current global population is estimated to be 8.3 million with little indication of decline.
 
Capture Rates


As a migrant species, capture of Pacific-slope Flycatcher occurs starting in April and continues through October. Capture rate (2010-2012; standardized as birds captured per 100 net hours) peaks substantially in August corresponding with dispersing juveniles and adults using Colony Farms as a foraging area before they continue their southern migration to the wintering grounds in Central America.


 

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