Yellow-bellied Flycatcher
Empidonax flaviventris

Montrose Point, Lincoln Park, Chicago
Cook County, IL
18 - 19 October 2008

At 9:00am on 18 Oct 2008, Paul Doughty, Nolan Lameka, and I found an Empidonax flycatcher at Montrose Point. The bird had a very noticeable eyering that in some views appeared to widen behind the eye, upperparts with a decidely greenish cast to them (though the bird was brightly lit in most views), very blackish primaries contrasting quite strongly with the body plumage and the wingbars and wing feather edges. We did not have any real opportunity to study the underparts as the bird was always facing away from us, but the pale areas of the bird that were visible (eyering, throat, chin, lower cheek) gave me the impression of some faint yellowish tones; however, this was not seen well. The bird flicked its wings and tail incessantly, with the tail motion upward and more pronounced than the downward motion of the wings. In the field one could see that the entire lower mandible was pale in color. During the entire period of my observations, the bird was silent.

Nolan had his camera and was able to get a set of images, five of which appear below. The fifth photo is very similar to the second. On 19 Oct 2008, Nolan relocated the bird at Montrose Point and obtained another set of photos, five of which appear below. Nolan commented that the flicking of the tail was even more noticeable on the second day than on the first. Nolan mentioned that Craig Millard also took photographs of the bird on 19 Oct 2008. Follow these links to see Craig's photographs:

Millard photo set A (6 images)

Millard photo set B (5 images)

Millard photo set C (3 images)

Millard photo set D (2 images)

Millard photo set E (5 images)

Millard photo set F (2 images)

Millard photo set G (13 images)

Millard photo set H (5 images)

Millard photo set I (1 image)

Millard photo set J (14 images)

Millard photo set K (1 image)

All of the photos below are Nolan Lameka's.

In this first photo from 18 Oct 2008 the green tones on the back do not show up as strongly as they did in the field, though they are somewhat apparent.


In this second photo there appears to be yellow tones in the eyering, and the broadening of the eyering behind the eye is apparent, and one can see that the lower mandible is pale to the tip.


In this third photo the edges to the secondaries show a yellow cast, which fits Yellow-bellied Flycatcher (Pyle et al., 1987; Gross and Lowther, 2001). The edging on secondaries of on the Western Flycatcher complex has been described as "pale grayish olive, grayish buff, or olive-buff" (Lowther, 2000a; Lowther, 2000b). However, almost all the other photos don't seem to show this (with the exception of the spread wing shot at the end), so perhaps it results from a lighting effect. The shape of the tail feathers is also clear in this photo; apparently this is an adult bird based on the depiction of tail shape in Pyle et al. (1987). (Michael Retter has also pointed out in an IL-Birds post that some of the photos show rather worn wing feathers, e.g. the wing covers in the fourth photo.) Again, the back shows less green in the photo than in life. The color of the chin see here, however, is like what I recall seeing in the field (that is, a vague hint of yellow, and not clearly white).


Another view of the bird in this fourth photo, and the only one from this day to show the underparts. There are at best vague hints of yellow in these.


This fifth photo is similar to the second, but we're zoomed in a little closer.


Here is the first photo from 19 Oct 2008. This is the only photo in either set in which the head is smoothly rounded as would be typical of Yellow-bellied Flycatcher. In all of the other photos, there is a slight crest on the head. This photo gives the best look of an apparent pale outer web on the outermost tail feather (which is at least hinted at in the first three photos from 18 Oct), though the strong light is at least enhancing that appearance here. It is mentioned in Whitney and Kaufmann (1986) that birds in the Western Flycatcher complex (i.e. Pacific-slope and Cordilleran) do not have such a pale outer web on this feather. However, the BNA account includes in the description of this group's appearance the following: "outer webs of rectrices light grayish olive or buffy olive on edges" (Lowther, 2000a; Lowther, 2000b), without any specific mention of the outer rectrices. Though much of the underparts are white, there are some areas with faint yellow, especially along the flanks.


The second photo from 19 Oct 2008. The underparts appear faintly yellow in this shot.


The third photo from 19 Oct 2008.


The fourth photo from 19 Oct 2008. Where did the (faint) yellowish tones on the underparts go?


Here's a fifth photo from 19 Oct 2008 (added here 20 Oct 2008), showing the spread wings of the bird. Here again, at least on the left wing, the edging of the secondaries appears yellow.

An Empidonax with these greenish and yellowish tones should be either a Yellow-bellied, an Acadian, or one in the Western Flycatcher complex. The structure appears wrong for Acadian, the tail is not very broad as it would be in an Acadian, and the repeated flicking of the tail and wings is not characteristic of Acadian. At this time of year an Acadian Flycatcher should also show buff wingbars, while adult Yellow-bellieds have whitish wingbars (Whitney and Kaufman, 1986).

It is possible that the outer tail feather's pale outer web rules out the unlikely possibility of a Western, but I can't find another reference other than Whitney and Kaufman (1986) that mentions this, and there is also the question whether it is correctly seen in the photos. The blackish primaries (shown best in the first, second, and fifth photos from 18 Oct) also seem supportive more for Yellow-bellied than for Western. Though the underparts appear less yellow than one would expect in Yellow-bellied, fall adults can show only weak yellow in the underparts (Whitney and Kaufman, 1986), and we are well into that season at this date. However, the bird most of the time appears slightly crested, which is better for Western. I don't think that the eyering shape helps settle the matter better Yellow-bellied and Western.

Yellow-bellied Flycatchers usually leave Illinois prior to the end of September. For the period from 1984 to 2007, the average departure date (statewide) is 28 September, and the median departure date is 27 September. As best I can determine right now, there are nine records for October or later, with three of these from the northern tier of the state. The table below lists the nine records.

County (tier)
21-23 Nov 2004
Cook (north)
Paul Clyne, Doug Stotz, Tom Schulenburg
13 Nov 1980
Sangamon (central)
Dave Bohlen
13 Oct 1975
Sangamon (central)
Dave Bohlen
9 Oct 1984
Sangamon (central)
Dave Bohlen
7 Oct 1990
Sangamon (central)
Dave Bohlen
3 Oct 1987
Sangamon (central)
Dave Bohlen
2 Oct 1987
Cook (north)
Harriet Rylaarsdam
2 Oct 2000
Putnam (north)
Doug Stotz
2 Oct 2003
Kankakee (central)
Jed Hertz


Paul Clyne graciously provided me with information about the record from Fall 1990 (added to the above table on 20 Oct 2008). I didn't have the relevant journal that covered that season (Illinois Birds & Birding, vol. 7 no. 2), but apparently Paul carries it with him while traveling and was able to supply me the datum from Macedonia.

Neither Cordilleran Flycatcher nor Pacific-slope Flycatcher has been recorded in Illinois.

Addtional remarks posted here 19 Dec 2008:

A couple of folks have remarked to me that it seems odd to have a Yellow-bellied Flycatcher being out in the open so much. I was bothered by this behavior, too, and at the time of the sighting. When I was looking at the bird as it perched on the fence post shown in the first couple of photos, I thought it was a really odd perch for a Yellow-bellied, but at the same time I was rather happy. It just sat there and I told Nolan to get a photo of that bird (figuring, well, since it was an empid in mid-October a photo could be handy). I rationalized my concerns about behavior away somewhat because the bird was on the outer edge of a particular grove of trees on the interior of which I have often seen Yellow-bellied Flycatchers. At this initial sighting on Saturday, we lost sight of the bird when it went inside this grove. But then on Sunday it merrily sat outside another grove of trees ..... Hmm.

Desante et al. (1985) discuss the separation of Yellow-bellied Flycatcher from Western Flycatcher on the basis of primary and tail feather lengths in the case of first-year females. However, this approach is probably not useful here because the sex of the bird isn't known, the age remains somewhat uncertain, and estimates of feather lengths from the photos may not be accurate enough.

A Western Flycatcher was found in Connecticut in fall of 2007. Here is a link to Mark Szantyr's photos this bird on 1 Dec 2007: Another photo of this bird is at the Connecticut Ornithological Association's webpage (scroll down to the bottom of the rare bird photos).

Seven individuals responded to my request for input on this bird in a post to the Frontiers of Field Identificaiton listserve. Here is a brief summary of comments provided.

As might be expected, no one was willing to make a definitive call as to specific identification. A couple of respondents from western North America felt that the bird would be readily taken as a Western-type if seen in its normal range. Some points raised as going against Yellow-bellied were

  • wings not strongly contrasting;
  • it's perched in the open on a fence post (but is this also unusual behavior for a Western?)
  • primary extension seems short;
  • brownish-green coloration;
  • the crested appearance;
  • very pale yellow tones.

On the issue of the birds age, responses were mixed. Four remarked explicitly on the age: two stated they felt it was an adult bird (one of these mentioning worn wing feathers), one indicated it's a young bird (on the basis of pointed rectrices), and one saw mixed evidence. This latter individual thought that though the retrix shape seems to indicate an adult, "based on the apparent condition of primaries, secondaries, and coverts, it looks more like a hatch-year bird. The edging on the secondaries and on the tips of the primaries still looks pretty fresh to me. And the tips of the greater & median coverts - the wingbars - just look too fresh & too broad to me to be 9-10 months old."

Addtional remarks posted here 2 Jan 2009:

Peter Pyle pointed me to his article with Matt Heindel (Heindel and Pyle, 1999). Information in this paper, especially regarding the wing formulae but also in regard to some other features, would seem to indicate that the Montrose Point bird is a Yellow-bellied Flycatcher. I will post more details about this when I have a chance to.

Addtional remarks posted here 17 Mar 2015:

Spurred by the publication of the work by Baumann et al. (2014), here is an update.

My review of Heindel and Pyle (1999) prompted a focus on the spacing of the primary gaps. That work noted that "The distance between p7 and p6 is longer in Yellow-bellied than in Western flycatcher, whereas the distances bewteen p6 and p6 and between p5 and p4 are similar but average larger in Western Flycatchers." On 7 Aug 2009, I visited the Field Museum of Natural History and measured primary spacings on 31 Pacific-slope Flycatcher, 21 Cordilleran Flycatcher, and 60 Yellow-bellied Flycatcher study skins. The measurements revealed that the ratio of the gap between p6 and p5 to the gap between p7 and p6 can help separate between Yellow-bellied and Pacific-slope/Cordilleran Flycatchers. If this ratio is two or greater, it's almost surely a Pacific-slope/Cordillaran, while a ratio of 1.5 or less means Yellow-bellied. Assessing this ratio from the photographs of the Montrose Point bird yielded ratios from 0.95 to 1.55, providing evidence in support of identification as a Yellow-bellied Flycatcher.

A couple years later, a 6 Nov 2011 post to ID-Frontiers by Tony Leukering and the subequent response by Joe Morlan brought to my attention another feature that would help: the extent of a dark bar between the edges of the secondary fringes and the lower wing bar, wider in Yellow-bellied than in Pacific-slope/Cordilleran. This feature on the Montrose Point bird again suggested Yellow-bellied, but at the time of these posts this field mark had not been quantified. The paper by Baumann et al. (2014) addressed this shortcoming, and at the same time exposed Illinois's first record of Pacific-slope/Cordilleran Flycatcher, which had been deposited in the Field Museum as a Yellow-bellied Flycatcher after having met its end in a collision with a McCormick Place window.


M.J. Baumann, S.C. Galen, N.D. Pederson, and C.C. Will, "Simple Technique for Distinguishing Yellow-bellied Flycatchers from Cordilleran and Pacific-slope Flycatchers," Journal of Field Ornithology, vol. 85, no. 4, pp. 391-396, 2014.

D.F. DeSante, N.K. Johnson, R. LeValley, R.P. Henderson, "Occurrence and Identification of the Yellow-bellied Flycatcher on Southeast Farallon Island, California," Western Birds, vol. 16, no. 4, pp. 153-160, 1985.

Gross, Douglas A. and Peter E. Lowther. 2001. Yellow-bellied Flycatcher (Empidonax flaviventris), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online:

M. Heindel and P. Pyle, "Identification of Yellow-bellied and 'Western' Flycatchers," Birders Journal, vol. 8, no. 2, pp. 78-87, 1999.

Lowther, Peter E. 2000a. Pacific-slope Flycatcher (Empidonax difficilis), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online:

Lowther, Peter E. 2000b. Cordilleran Flycatcher (Empidonax occidentalis), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online:

P. Pyle, S.N.G. Howell, R.P. Yunick, D.F. DeSante, Identification Guide to North American Passerines. Bolinas, CA: Slate Creek Press, 1987.

B. Whitney and K. Kaufman, "The Empidonax Challenge, Part IV," Birding, vol. 18, no. 6, pp. 315 - 327, December 1986.

This page was last updated on 17 March 2015.
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