Western 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 most Empidonax 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. DNA testing in 2014 confirmed a new field mark, involving the extent of buffy edging on the secondaries, to reliably distinguish this species from the yellow-bellied flycatchers. The song includes notes represented as pseet, ptsick, seet usually sung rapidly together. In Pacific birds, the ptsick or ptik 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 distinctive pit pete or tse-seet, but some give a "rising tsweep" or a "slurred tseeweep".

These birds migrate to Mexico for the winter, where the Mexican central-southern birds are resident. The non-resident birds are on the western coast from Jalisco northwards, and then to inland regions, in a corridor strip on the western flank of the Sierra Madre Occidental.

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 or mosquitoes. They fulfill an important role in keeping insect populations in check, particularly mosquitoes, and they also eat caterpillars and spiders.