| Western flycatcher | |
|---|---|
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Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Family: | Tyrannidae |
| Genus: | Empidonax |
| Species: | E. difficilis |
| Binomial name | |
| Empidonax difficilis Baird, 1858 | |
| Synonyms | |
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Thewestern flycatcher (Empidonax difficilis) is a smallinsectivorous bird in the familyTyrannidae. It is native to westernNorth America, where it breeds in theRocky Mountains and Pacific Coast forests and mountain ranges fromCalifornia toAlaska and south to centralMexico; northern populations migrate south to Mexico for the winter.[2]
The western flycatcher was recognized as a single species until 1989, when theAmerican Ornithologists’ Union split it into two different species: thePacific-slope flycatcher (E. difficilis) of coastal western North America and parts of the western Rocky Mountains, and theCordilleran flycatcher (E. occidentalis) of the interior Rocky Mountains, with both species wintering in Mexico. Both species looked virtually identical to one another, with the split being based on differing breeding habitats and apparent differences in songs and calls. The split was recognized until 2023, when the American Ornithologists’ Union andInternational Ornithological Congress again lumped both species due to a lack of consistent vocal, genetic, morphological differences and extensive hybridization across much of their range.[3][4][5]
There are five subspecies recognized:[2]
The latter two subspecies were previously thought to comprise the "Cordilleran flycatcher".
Adults have olive-gray upperparts, darker on the wings and tail, with yellowish underparts; they have a conspicuous teardrop-shaped white eye ring, white wing bars, a small bill and a short tail. It differs only subtly from mostEmpidonax flycatchers in North America, but its breeding habitat and call are different. Many species of this genus look closely alike. The best ways to distinguish species are by voice, by breeding habitat, and by range.[6]
DNA testing in 2014 confirmed a new field mark, involving the extent of buffy edging on the secondaries, to reliably distinguish this species from theyellow-bellied flycatchers.[7][8]
The song includes notes represented aspseet,ptsick,seet usually sung rapidly together. In Pacific birds, theptsick orptik note has the first syllable higher-pitched than the second—this was previously seen as the only difference between their calls and those of the "Cordilleran" flycatcher (Sibley 2000). The male's typical position call is a loud and distinctivepit pete[citation needed] ortse-seet, but some give a "risingtsweep" or a "slurredtseeweep".
These birdsmigrate toMexico for the winter, where the Mexican central-southern birds areresident. The non-resident birds are on the western coast fromJalisco northwards, and then to inland regions, in acorridor strip on the western flank of theSierra Madre Occidental.
The western flycatcher inhabits either coniferous or deciduous forests. In its range it entersmixed woods,Douglas fir forests,redwood forests,pine-oak forests, and many other wooded environments includingriparian woodlands. As of November 2019, there has been one case of these West Coast birds showing up on the East Coast, in Palmyra, New Jersey.[9] The preferred breeding habitat is usually near running water. They make acup nest on a fork in a tree, usually low in a horizontal branch. Females usually lay two to five eggs.
As a flycatcher it will wait on a perch and when it sees a flying insect it will fly out to catch it in flight (hawking), and will also pluck insects from foliage while hovering (gleaning). They also enter swarms of gnats ormosquitoes. They fulfill an important role in keeping insect populations in check, particularly mosquitoes, and they also eat caterpillars and spiders.
