Cordilleran Flycatcher, Empidonax occidentalis

Cordilleran Flycatcher, Empidonax occidentalis occidentalis. Photograph taken within the wilds of Sinaloa, April 2019. Photograph and identification courtesy of David F. Smith, Alamos, Sonora.

The Cordilleran Flycatcher, Empidonax occidentalis occidentalis, is one of two subspecies of Cordilleran Flycatcher, 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. They are known in Mexico as mosquero cordillerano.

The Cordilleran 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 upperwing coverts, pale yellowish lores, a white eye ring with a yellowish tinge, the tail is grayish brown, 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, and their legs are gray and their feet and dusky brown to brownish black.

The Cordilleran Flycatcher one subspecies 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.

The Cordilleran Flycatcher is very similar to and cannot be distinguished from the Pacific-slope Flycatcher, Empidonax difficilis, and is only possible via voice and range.

The Cordilleran Flycatcher are 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 Cordilleran Flycatcher are complete medium-distance migrants, breeding primarily in the western United States, and overwintering in Mexico. Southern populations are year-round residents. They 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. The Cordilleran Flycatcher is poorly studied and very little about their biology and behavior patterns has been documented.

From a conservation perspective the Cordilleran Flycatcher is currently considered to be of Least Concern with stable, widely distributed populations.