The Pacific-slope flycatcher (Empidonax difficilis) is a small insectivorous bird of the family Tyrannidae. It is native to coastal regions of western North America, including the Pacific Ocean and the southern Gulf of California, as far north as British Columbia and southern Alaska, but is replaced in the inland regions by the Cordilleran flycatcher. These two species were classified as a single species, commonly called the western flycatcher, by the American Ornithologists’ Union until 1989. In winter, both species migrate south to Mexico, where they are virtually indistinguishable from one another.
In plumage, the Pacific-slope flycatcher is virtually identical to the Cordilleran flycatcher, and differs only subtly from most Empidonax flycatchers in North America, but its breeding habitat and call are different. Its call can vary slightly by different regions and the bird itself.
The Pacific-slope flycatcher inhabits either coniferous or deciduous forests. In its range it enters mixed woods, Douglas fir forests, redwood forests, and many other wooded environments including riparian 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.
As a flycatcher it will wait on a perch and when it sees a flying insect it will chase it without any apparent effort. They also enter swarms of gnats, mosquitos and wherever such insects congregate. They fulfill an important role in keeping insect populations in check, particularly mosquitoes, and they also eat caterpillars and spiders.
- BirdLife International (2019). "Empidonax difficilis". IUCN Red List of Threatened Species. 2019: e.T22699871A137994099. doi:10.2305/IUCN.UK.2019-3.RLTS.T22699871A137994099.en. Retrieved 12 November 2021.
- Pieplow, Nathan. "The "Western" Flycatcher Problem". Earbirding. Retrieved 2019-03-14.
- "Pacific-slope Flycatcher - eBird". ebird.org. Retrieved 2020-09-25.