Western Flycatcher, Empidonax difficilis
Western Flycatcher, Empidonax difficilis. Photograph taken within the wilds of Sinaloa, April 2019. Photograph and identification courtesy of David F. Smith, Alamos, Sonora.
Background and Identification
The Western Flycatcher, Empidonax difficilis, is one of two subspecies, both of which are found in Mexico. They are a member of the Tyrannidae Family of Tyrant Flycatchers, which has four hundred twenty-five members placed in one hundred one genera, and in one of fifteen global species of the Empidonax Genus. In 2023, ornithologists lumped Pacific-slope and Cordilleran Flycatchers together as Western Flycatchers after treating them as separate species since 1989. Western Flycatchers actively forage on insects caught in the air or sally-gleaned from foliage of shrubs and trees. They have life spans of up to six years. They are known in Mexico as Mosquero del Pacífico.
The Western Flycatcher is small in stature. They are a nondescript green color with a teardrop-shaped eye ring. They are difficult to identify, with the most recognizable trait being their habit of flicking their tail upward when perched. They have yellowish olive to brownish olive underparts, sides of the head and neck and upper wing coverts, pale yellowish lores, a white eye ring with a yellowish tinge, the tail is grayish brown, and the wings have two distinct wing bars. Their chin and throat are pale grayish-yellow to yellowish-white. The breast and sides are pale buffy olive or whitish to lemon. Their upper mandible is brownish black, and the lower mandible is entirely yellow or pinkish, their iris is brown, their legs are gray and their feet and dusky brown to brownish black.
Habitat and Geographical Range
The Western Flycatcher is found in cooler habitats, arid, dense boreal forests of fir, pine and spruce associated with water courses at elevations between 1,000 m (3,300 feet) and 3,500 m (11,500 feet). Northern populations of Western Flycatchers are complete medium-distance migrants, breeding primarily in the western United States, and overwintering in Mexico. Southern populations are year-round residents.
Geographically, the Western Flycatcher is commonly found in inland forests, particularly in the Rocky Mountains and nearby ranges, stretching from Canada to Mexico. In Mexico, the Western Flycatcher is found within the Sierra Madre Occidental Mountains of Sonora and Chihuahua and northern Coahuila and winters south to central Oaxaca. The occidentalis subspecies is found within the highlands from Durango, southeast Sinaloa, southeast Coahuila, and Nuevo León south to Guerrero, southcentral Oaxaca, and western Veracruz.
Common Misidentifications
The Western Flycatcher historically has been considered to be a distinct species from the Pacific-slope Flycatcher, Empidonax difficilis, and the Cordilleran Flycatcher, Empidonax occidentalis. The two species (Pacific-slope and Cordilleran) were only distinguishable based on their different geographical ranges. The plumage and size of these species are almost entirely identical, and ornithologists grouped them into one species, the Western Flycatcher, in 2023. All species in the Empidonax genus are visually very similar. Common misidentifications that occur with other “Empidonax” species such as the Hammond’s Flycatcher, Empidonax hammondii, Dusky Flycatcher, Empidonax oberholseri, and the Willow Flycatcher, Empidonax traillii, all of which have subtle differences in size, call, and habitat preferences. Due to their almost identical appearance, proper identification often relies on vocalizations and geographic range, it is hard to tell flycatchers apart.
Conservation Perspective
From a conservation perspective the Western Flycatcher is currently considered to be of Least Concern with stable, widely distributed populations. However, like many species, they are affected by habitat loss, particularly the destruction of forests and riparian areas. Conservation efforts focus on protecting their breeding and wintering habitats to ensure long-term population stability.