Sighting Record for Utah

Common name:	Least Flycatcher
Scientific name:	Empidonax minimus
Date:	8 Jun 2013
Time:	~1:15 PM and ~4:45 PM
Length of time observed:	about 1 hour total over two periods
Number:	1
Age:	[unspecified]
Sex:	[unspecified]
Location:	Icon River Trail, Logan (west of 1000W at about 1500S)
County:	Cache
Latilong:
Elevation:
Distance to bird:	down to ~25 feet
Optical equipment:	Nikon 10x42 binoculars and Nikon SLR with 80-400mm lens
Weather:	Sunny, warm.
Light Conditions:	Mostly in shade of dense riparian canopy.
Description: Size of bird:
(Description:) Basic Shape:
(Description:) Overall Pattern:
(Description:) Bill Type:
(Description:) Field Marks and Identifying Characteristics:	Easily identified as one of the Empidonax genus flycatchers by whitish wing bars, short primary projection, overall drab coloration, yellowish-olive on belly, grayish chest, whitish throat, and brownish-olive back. Several Western Wood-Pewees were present for direct comparison. See "similar species," photos, and audio recording for separation from other Empidonax flycatchers. (see photos)
Song or call & method of delivery:	Singing frequently and persistently during most of the observation period, with breaks of a couple minutes at times. Typical distinctive "che-BEK" song with little to no variation in the repetition of this phrase. Also gave a few "whit" calls in the second observation period, but not the first. Audio recording of song submitted with this record.
Behavior:
Habitat:	Riparian zone along the Logan River. Nearly complete canopy of mostly tall willows. This bird tended to forage in the mid-canopy (roughly 20 feet over ground level), rarely coming down to near ground level or moving up into the upper canopy.
Similar species and how were they eliminated:	Song is the easiest way to distinguish Least Flycatcher from the other Empidonax flycatchers, and this bird was singing frequently. Some phrases of other Empid songs can sound like "che-BEK" but they eventually switch to other song phrases; this bird gave only the "che-BEK" phrase over about an hour of total observation time. The audio recording submitted with this record represents the song better than I could in writing. The morphology of this bird also supported Least Flycatcher to the exclusion of other Empidonax. The bird was small and had a distinct eye ring, eliminating Alder Flycatcher and Willow Flycatcher. (A Willow Flycatcher was seen at the same location on the same visit.) The tail flicked up, and the bill was too small for Gray Flycatcher, which also tends to be less brightly colored than this bird on the belly and to have less distinct wing bars. "Western" Flycatcher (Cordilleran and Pacific-slope, collectively) tend to be much yellower overall than this bird, and have a more almond-shaped eye ring, extending behind the eye and often breaking above the eye, whereas this bird had a very even eye ring that was not broken at the top or elongated behind the eye. Song also eliminates Western Flycatcher. Yellow-bellied Flycatcher is also much more yellow than this bird, although the bill size and coloration are similar. Song also eliminates Yellow-bellied Flycatcher. Hammond's Flycatcher has long primary projection, but this bird had medium-short primary projection, and Hammond's tend to have a rather dark lower mandible, but this bird's lower mandible was nearly completely yellow-orange, with a very diffuse dusky tip that was not noticeable in most lighting conditions. The bill of Hammond's Flycatcher is also smaller, and especially narrower in width, than that of this bird. Dusky Flycatcher is probably the most difficult Empid to eliminate, but tends to have more obvious dusky tip to the lower mandible, sometimes covering most of the mandible. Dusky Flycatcher tends to have a slightly larger bill than Least Flycatcher, but I believe this bird was a bit on the larger end of the Least Flycatcher spectrum, and probably in the range of overlap of total bill length. Dusky Flycatcher is also slightly larger than Least Flycatcher, but was not seen in direct comparison with this bird (although Duskies were seen elsewhere on the same day). The combination of relatively short, broad bill, almost entirely yellow-orange lower mandible, distinct contrast in tertials, and smallish size together point towards Least Flycatcher and away from Dusky Flycatcher, but the song (recorded) is the best indication of Least over Dusky.
Previous experience with this & similar species:	This is only my third observation of Least Flycatcher (my two other observations being from Illinois and Wisconsin). I have extensive experience with the expected Empidonax flycatchers in Utah.
References consulted:	National Geographic Field Guide to the Birds of Western North America.
Description from:	Photos, audio recording, and memory
Observer:	Ryan O'Donnell
Observer's address:	1098 Crescent Dr
Observer's e-mail address:	**
Other observers who independently identified this bird:	First spotted by Kendal Morris and then identified by myself, Leah Lewis, Andrew Durso, and Kendal on 8 Jun 2013. Subsequent observers include at least Mike Fish (9 Jun 2013) and Bob Atwood (10 Jun 2013).
Date prepared:	10 Jun 2013
Additional material:	Photos and audio recording attached. Please withhold the audio recording from public distribution until the bird has left the area.
Additional_Comments:	Note: eBird checklists for this observation: http://ebird.org/ebird/view/checklist?subID=S14370687 and http://ebird.org/ebird/view/checklist?subID=S14372276