Sighting Record for Utah

Common name:	Pacific-slope Flycatcher
Scientific name:	Empidonax difficilis
Date:	5/12/21
Time:	11:30 am
Length of time observed:	5 min
Number:	1
Age:	AHY
Sex:	M
Location:	Fish Springs NWR
County:	Juab
Latilong:	39.850032, -113.396011
Elevation:	4321ft
Distance to bird:	30 yards
Optical equipment:	Pentax ED 8x43
Weather:	Warm and sunny- around 75.
Light Conditions:	Harsh overhead light
Description: Size of bird:	Small passerine.
(Description:) Basic Shape:	Upright perching bird with crested head.
(Description:) Overall Pattern:	Olive upperparts gradng into yellowish underparts.
(Description:) Bill Type:	Short, thin bill.
(Description:) Field Marks and Identifying Characteristics:	I initially heard the bird calling from low in a cottonwood but calling from the interior of the tree and not giving great views. When I was able to see it, I could tell it was a Western Flycatcher due to the crested head, yellowish underparts and teardrop shaped eyering. Knowing that Pacific Slope flycatchers prefer to migrate in desert lowlands vs Cordilleran's preference for migrating in more upland areas, I eventually was able to record the vocalization. Upon looking at the spectrogram, the call matches Pacific-slope and was different from even the extreme monosyllabic version of certain Cordillerans which usually have a 2 part call. (see eBird checklist)
Song or call & method of delivery:	The bird was delivering the male position note. Upon viewing the spectrogram, the call was shown to be a single kinked note which is characteristic of Pacific Slope Flycatcher rather than a Cordilleran which usually give a 2 part position call but will sometimes give a single note position call but this note will never show a kink or flat section in the middle.
Behavior:	Foraging low in the interior of a cottonwood at Horse Springs at Fish Springs NWR. Rarely gave good looks and called occasionally.
Habitat:	Desert oasis migrant trap in the middle of the West Desert. Tall cottonwoods around some spring-fed ponds ringed in cattails and other vegetation. Surrounding area was desert scrub.
Similar species and how were they eliminated:	Cordilleran Flycatcher is the only other empid that could be confused with this species since they essentially look identical and can only be differentiated by voice. Pacific-slope Flycatchers also prefer to migrate in desert lowlands in Arizona and Nevada whereas Cordillerans prefer to migrate in upland areas. Cordillerans will usually give a 2 part position call but will sometimes give a single note position call but this note will never show a kink or flat section in the middle on the spectrogram. Pacific-slope position call is a single upslurred note with a kink or flat section in the middle. I made a pdf reference guide to show the differences in the position notes between Cordilleran and Pacific-slope Flycatchers and even the extreme version of Cordilleran Flycatcher. My recording of the Pacific-slope Flycatcher is H showing the single upslurred note with the first call showing a flat middle section and the second showing a slight kink in the middle. The Pacific-slope calls in C,D,E&I show the kink or flat section in the single note male position call. My calls look quite similar to the recordings in D with less of a kink than in other recordings. [Note that the spectrograms in the recordings of I are compressed and look shorter than they actually are. The other spectrograms shown the more typical looks of the calls. The typical two-part Cordilleran male position call is shown by A,B&F. G shows the extreme of the monosyllabic, one note version of the male Cordilleran position call. Even in the extreme, the call is a continuous upslurred note without a kink or flat section in the middle. The calls I recorded show a flat or kinked section in the middle, unlike what the extreme version of a Cordilleran.
Previous experience with this & similar species:	I've seen many Cordilleran Flycatchers in Utah. I've had a few Pacific-slope Flycatchers in the Lytle Ranch area in extreme southwestern Utah and many Pacific-slopes in the Seattle area.
References consulted:	Sibley's 2nd edition. Peterson Field Guide to Bird Sounds of Western North America. Also the following webpages: http://earbirding.com/blog/archives/2996 http://www.appliedbioacoustics.com/research/wefl/frameindex.html
Description from:	Notes taken at the time of the sighting
Observer:	Kenny Frisch
Observer's address:	4609 S Wallace Ln Holladay
Observer's e-mail address:	**
Other observers who independently identified this bird:	N/A.
Date prepared:	8/12/21
Additional material:	PDF reference guide with my recording compared to others
Additional comments:	The ebird checklist with a recording of the call can be found here: https://ebird.org/checklist/S87956412.