By: Jenna Curtis, KBO Research and Monitoring Intern
Formerly grouped with the Cordilleran Flycatcher as “Western Flycatchers”, the Pacific-slope Flycatcher (Empidonax difficilis) was recognized as a unique species in 1989. Though vocally and morphologically distinct, it is still challenging for many birders to distinguish this species from the visually similar Cordilleran. In fact, the Pacific-slope Flycatcher’s name “difficilis” refers to how difficult it is to separate this species from its more easterly cousin!
The Pacific-slope Flycatcher is a common breeder in low and midelevation forests. This species is often associated with riparian, or streamside habitats, and has been found to prefer mature and old growth forests. Its breeding range extends from southern Alaska to Baja California. In winter, the Pacific-slope Flycatcher migrates to central and western Mexico, where its territories commonly overlap with the Cordilleran Flycatcher.
As the name implies, the Pacific-slope Flycatcher’s diet consists primarily of flying insects, which it catches by “hawking” – flying up to grab insects from a central perch – or by gleaning from leaves and branches. The small size and yellow-green color of this species makes it hard to spot in shady forests. It is more often identified by the high pitched, nasally “Pst-SEET pstick seet!” song given by advertising males. The Pacific-slope Flycatcher is a Partners in Flight stewardship species and is one of the species being monitored by our long-term monitoring program within the Klamath Network National Parks. KBO monitoring data show that the Pacific-slope Flycatcher is the most commonly detected species in Redwood National and State Parks, where it is strongly associated with redwood forests. There are some indications that the Pacific-slope Flycatchers is declining in moist forests of the Pacific Northwest. Continued monitoring and collaborative efforts to conserve the moist, late-successional forests inhabited by this bird will be needed to maintain healthy Pacific-slope Flycatcher populations.
This article appears in the Summer 2012 Newsletter.
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General Reference. Corvallis: Oregon State University
Press, 2003.; Lowther, Peter E. 2000. Pacific-slope
Flycatcher (Empidonax difficilis), The Birds of North America
Online (A. Poole, Ed.). Cornell Lab of Ornithology, Ithaca,
NY.; Partners in Flight North American Landbird
Conservation Plan. Cornell Lab of Ornithology, Ithaca, New