Pacific-slope Flycatcher
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The western flycatcher (''Empidonax difficilis'') is a small
insectivorous A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant which eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores we ...
bird in the family
Tyrannidae The tyrant flycatchers (Tyrannidae) comprise a Family (biology), family of passerine birds which is found virtually throughout North America, North and South America. It is the world's largest family of birds, with more than 400 species, and is ...
. It is native to western
North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
, where it breeds in the
Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in great-circle distance, straight-line distance from the northernmost part of Western Can ...
and Pacific Coast forests and mountain ranges from
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
to
Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...
and south to central
Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
; northern populations migrate south to Mexico for the winter.


Taxonomy

The western flycatcher was recognized as a single species until 1989, when the
American Ornithologists’ Union The American Ornithological Society (AOS) is an ornithology, ornithological organization based in the United States. The society was formed in October 2016 by the merger of the American Ornithologists' Union (AOU) and the Cooper Ornithological S ...
split it into two different species: the Pacific-slope flycatcher (''E. difficilis'') of coastal western North America and parts of the western Rocky Mountains, and the Cordilleran flycatcher (''E. occidentalis'') of the interior Rocky Mountains, with both species wintering in Mexico. Both species looked virtually identical to one another, with the split being based on differing breeding habitats and apparent differences in songs and calls. The split was recognized until 2023, when the American Ornithologists’ Union and
International Ornithological Congress International is an adjective (also used as a noun) meaning "between nations". International may also refer to: Music Albums * ''International'' (Kevin Michael album), 2011 * ''International'' (New Order album), 2002 * ''International'' (The T ...
again lumped both species due to a lack of consistent vocal, genetic, morphological differences and extensive hybridization across much of their range.


Subspecies

There are five subspecies recognized: *''E. d. difficilis'', from southeastern Alaska south to the Sierra San Pedro Mártir of Baja California, Mexico *''E. d. insulicola'', the Channel Islands of southern California * ''E. d. cineritius'', mountains of southern Baja California Sur, Mexico * ''E. d. hellmayri'', Breeds in the interior Rockies from Canada south to northern Mexico, winters in central and southern Mexico * ''E. d. occidentalis'', the Sierra Madre del Sur of Guerrero and southern Oaxaca, Mexico The latter two subspecies were previously thought to comprise the "Cordilleran flycatcher".


Description

Adults have olive-gray upperparts, darker on the wings and tail, with yellowish underparts; they have a conspicuous teardrop-shaped white eye ring, white wing bars, a small bill and a short tail. It differs only subtly from most ''Empidonax'' flycatchers in North America, but its breeding habitat and call are different. Many species of this genus look closely alike. The best ways to distinguish species are by voice, by breeding habitat, and by range. DNA testing in 2014 confirmed a new field mark, involving the extent of buffy edging on the secondaries, to reliably distinguish this species from the
yellow-bellied flycatcher The yellow-bellied flycatcher (''Empidonax flaviventris'') is a small insect-eating bird of the tyrant flycatcher family. Description Adults have greenish upperparts and yellowish underparts (especially on the throat), with a dusky wash on th ...
s. The song includes notes represented as ''pseet'', ''ptsick'', ''seet'' usually sung rapidly together. In Pacific birds, the ''ptsick'' or ''ptik'' note has the first syllable higher-pitched than the second—this was previously seen as the only difference between their calls and those of the "Cordilleran" flycatcher (Sibley 2000). The male's typical position call is a loud and distinctive ''pit pete'' or ''tse-seet'', but some give a "rising ''tsweep''" or a "slurred ''tseeweep''".


Distribution

These birds
migrate Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...
to
Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
for the winter, where the Mexican central-southern birds are
resident Resident may refer to: People and functions * Resident minister, a representative of a government in a foreign country * Resident (medicine), a stage of postgraduate medical training * Resident (pharmacy), a stage of postgraduate pharmaceut ...
. The non-resident birds are on the western coast from
Jalisco Jalisco, officially the Free and Sovereign State of Jalisco, is one of the 31 states which, along with Mexico City, comprise the 32 Political divisions of Mexico, Federal Entities of Mexico. It is located in western Mexico and is bordered by s ...
northwards, and then to inland regions, in a corridor strip on the western flank of the
Sierra Madre Occidental The Sierra Madre Occidental is a major mountain range system of the North American Cordillera, that runs northwest–southeast through northwestern and western Mexico, and along the Gulf of California. The Sierra Madre is part of the American C ...
.


Habitat

The western flycatcher inhabits either coniferous or deciduous forests. In its range it enters
mixed woods Temperate broadleaf and mixed forest is a temperate climate terrestrial habitat type defined by the World Wide Fund for Nature, with broadleaf tree ecoregions, and with conifer and broadleaf tree mixed coniferous forest ecoregions. These for ...
, Douglas fir forests, redwood forests,
pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. ''World Flora Online'' accepts 134 species-rank taxa (119 species and 15 nothospecies) of pines as cu ...
-
oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...
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. The preferred breeding habitat is usually near running water. They make a
cup nest A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American robin or Eurasian bl ...
on a fork in a tree, usually low in a horizontal branch. Females usually lay two to five eggs.


Diet

As a flycatcher it will wait on a perch and when it sees a flying insect it will fly out to catch it in flight ( hawking), and will also pluck insects from foliage while hovering (
gleaning Gleaning is the act of collecting leftover crops in the field after harvest. During harvest, there is food that is left or missed often because it does not meet store standards for uniformity. Sometimes, fields are left because they were not ec ...
). They also enter swarms of gnats or
mosquitoes Mosquitoes, the Culicidae, are a family of small flies consisting of 3,600 species. The word ''mosquito'' (formed by '' mosca'' and diminutive ''-ito'') is Spanish and Portuguese for ''little fly''. Mosquitoes have a slender segmented body, ...
. They fulfill an important role in keeping insect populations in check, particularly mosquitoes, and they also eat caterpillars and spiders.


References

*


External links


Videos, photos, and sounds
at the Internet Bird Collection

at USGS

VIREO * ttp://www.bobsteelephoto.com/Species/psfl.html Article with photosat Bob Steele Phoptography * ttp://ibc.hbw.com/ibc/phtml/especie.phtml?idEspecie=5003 Videos, photos and sounds- Internet Bird Collection
Photos
- VIREO
Photo-High Res

PhotoArticle
fwp.mt.gov (Montana Fish, Wildlife & Parks) {{Taxonbar, from=Q585125
Western flycatcher The western flycatcher (''Empidonax difficilis'') is a small insectivorous bird in the family Tyrannidae. It is native to western North America, where it breeds in the Rocky Mountains and Pacific Coast forests and mountain ranges from California ...
Fauna of the California chaparral and woodlands Native birds of Alaska Native birds of the Northwestern United States Native birds of the West Coast of the United States Native birds of Western Canada Native birds of the Rocky Mountains Birds of the Great Basin Birds of the Rio Grande valleys Pacific-slope flycatcher Birds of the Sierra Madre Occidental Meso-American wintering birds Pacific-slope flycatcher