Cordilleran Flycatcher

The Cordilleran Flycatcher (Empidonax occidentalis) is a small, insectivorous songbird native to the mountain forests of western North America. It is a member of the notoriously difficult-to-identify genus Empidonax, which contains several species that are nearly identical in physical appearance. For many years, the Cordilleran Flycatcher and the Pacific-slope Flycatcher were considered a single species called the 'Western Flycatcher'. They were split in 1989 due to differences in vocalizations, genetics, and geographic range, but were recently lumped back together as the Western Flycatcher (Empidonax difficilis) by the American Ornithological Society in 2023. Despite this taxonomic update, birders still widely recognize and track the 'Cordilleran' form for its distinct geographic range, ecological preferences, and unique vocal signatures.

Identifying the Cordilleran Flycatcher by sight alone requires a keen eye for subtle plumage details.

Key Field Marks

• Eye Ring: Features a prominent, bold white eye ring that is distinctly teardrop- or almond-shaped, tapering to a point behind the eye.
• Coloration: Overall olive-green to olive-grey upperparts with a yellowish wash across the belly and breast, and a yellowish-throat (unlike many other Empidonax flycatchers which have white or gray throats).
• Bill: The lower mandible is long, broad, and entirely bright yellow-orange.
• Wings: Displays two pale yellowish-white wingbars and a moderate primary feather projection.

Similar Species

• Pacific-slope Flycatcher: Virtually identical in appearance. Visually indistinguishable in the field. Separation is achieved through geographic location (coastal vs. interior) and male vocalizations.
• Hammond's Flycatcher: Has a smaller, darker bill, greyish throat, shorter primary projection, and a rounder, more symmetrical eye ring.
• Dusky Flycatcher: Features a more greyish plumage, a smaller bill with a dark tip on the lower mandible, and a round eye ring.

During the breeding season, the Cordilleran Flycatcher is found in shady, moist, high-elevation habitats.

Preferred Habitats

It is highly associated with pine-oak forests, mixed-conifer forests, wooded canyons, and steep mountain ravines, often near rushing streams. They prefer areas with dense understory and rocky cliffs or banks, which provide excellent nesting sites.

Range and Migration

• Breeding Range: Found throughout the Rocky Mountain region and the Intermountain West, extending from southern British Columbia and Alberta down through Montana, Wyoming, Colorado, and into the mountains of Mexico.
• Wintering Range: Migrates south to winter in the pine-oak forests and tropical deciduous woodlands of western Mexico.
• Migration Timing: They are nocturnal migrants, traveling north in late spring (May) and returning south by late summer or early autumn (August to September).

Feeding

Like other flycatchers, this species utilizes a 'sallying' foraging strategy. It perches quietly on a low or mid-canopy branch, scanning for insects, and then darts out rapidly to snatch prey mid-air before returning to the same or a nearby perch. It will also glean insects and spiders directly from foliage and bark.

Vocalization

The most reliable way to identify the Cordilleran Flycatcher is by its voice. The male's territorial call is a high-pitched, two-syllabled, rising whistle described as 'pit-peet' or 'pith-eet', with a distinct pause between syllables. In contrast, the Pacific-slope Flycatcher's corresponding call is a single-syllable, slurred 'seet'. The song of the Cordilleran is a rapid, squeaky series of three distinct parts: a low note, a high thin slur, and a sharp peak.

Nesting and Breeding

Nests are built in highly sheltered locations, including ledges on rocky cliffs, dirt banks, tree cavities, branches of conifers, and occasionally on human structures like cabin porches. The nest is an open cup constructed from moss, grass, bark shreds, and lichen, lined with softer materials like hair and fine grass. The female lays 3 to 4 white eggs speckled with brown, incubating them for about 14-16 days.