BIRDING BY HINDSIGHT: A Second Look at Flycatchers
Flycatchers? You've got to be kidding. At the time of this writing, it's 25 below in northern Minnesota, hardly the weather for flycatchers. I'm going to have to think about this. Maybe there's something in the last issue of The Loon to inspire something more timely. . . .
Here you go: Carrol Henderson's interesting article about Trumpeter Swans, "The Case of the Rotten Swan" (The Loon 80:121-128). Now, there's a bird you can see presently in spite of below-zero temperatures, but be aware that the article presents a field mark that won't "hold up in court," to use Carrol's phrase. The text states, "The edge of the mandible (the tomium) is red on a Trumpeter Swan and black on a Tundra Swan," and three photo captions also reiterate this as a difference between the swans. Actually, however, many Tundras also show a reddish tomium, and this may lead to them being mistaken for Trumpeters.
While some of the field marks presented in the article to separate Trumpeters from Tundras are rightly described as only suggestive and not diagnostic, this one is not qualified as it should be. For some examples of Tundras with reddish-edged mandibles, go to Google Image Search (http://images.google.com), type in Tundra Swan, and you'll find several photos showing such color on Tundra Swan mandibles.
Well, that didn't take long. Not nearly enough for a Hindsight article, so I might as well talk about flycatchers. And if I start with wood-pewees, this installment will actually have some sense of timing, since soon I won't have Birding magazine to kick around any more. After some 40 uninterrupted years of receiving this magazine, I finally decided to drop my subscription, and this will be my last opportunity to whine about it. (For sale: a complete set of 240 issues of Birding, 1969-2008.)
I've complained about this journal before in this column (http://mbwbirds.com/id-journals-ii.html) – far too few ID articles in recent years, photos and captions and text often inconsistent with each other, and those artificial Photo Quiz exercises. Further, its now-infrequent ID articles have a tendency to be too narrow in focus, unhelpful, or sometimes even discredited, and the September-October 2008 issue included yet another such article: "Field Identification of Western & Eastern Wood-Pewees."
You'd think that an article devoted to wood-pewee identification would be welcome, given the well-known difficulty in separating the two species, and there are documented Minnesota records of Western Wood-Pewee. But once I saw who the authors were, I was prepared to be disappointed – two of them had also produced those dubious dowitcher articles discussed in previous Hindsight installments. (Normally, I'd cite The Loon references here, but we're all really better off not being reminded of the dowitcher mess.)
To its credit, the article does begin with an emphasis on vocalizations: "Voice is the most reliable criterion for identifying wood-pewees." But it really should have said it's the only reliable criterion, and left it at that. It also would have been better if something were said about the contact calls of juvenile Eastern Wood-Pewees, which can sound hoarse, burry, and reminiscent of the Western's song, though not as loud and not down-slurred (see http://mbwbirds.com/field-notes-ii.html).
Again, the problem of wood-pewee ID has long been studied and debated, and vocalizations have remained the only diagnostic and consistent difference between the two species. It's also been known and written that there is a tendency for Westerns to have darker underparts and darker lower mandibles, but, as the article correctly reiterates, there is lots of overlap in these two features, and they cannot be relied on.
So far, so good. But (as they did with the dowitchers) the authors press on to propose other "new" field marks, and it's hard to tell if these are consistent, merely suggestive, or mostly useless. They claim that an Eastern Wood-Pewee has two wing bars of equal brightness, while the upper wing bar on a Western is fainter than the lower. This difference isn't even qualified and almost sounds diagnostic when they say it is "more reliable" and "does indeed hold [up]". However, this is a pretty subtle feature, not really apparent in the composite photo of the two pewees on the magazine's cover, and subject to variations in feather wear (wing bars are among the first things to go on a bird in worn plumage).
At least the article qualifies its other two claims, but I don't consider their caveats strong enough. A difference is discussed in their ratios of primary extension beyond the tertials vs. tail extension beyond the primaries, but none of this is supported by the cover photo, the color illustration on the article's first page, or that dark, dingy photo of specimens. Equally dubious is that there any consistent difference in posture – Western's tail held higher in line with the back; Eastern's tail held lower. If this is valid, why doesn't the cover photo show any difference?
I'd be less critical of this article if it had stressed the similarity of wood-pewees to Alder and Willow flycatchers (like a pewee, these Empids show little or no eye ring); to Olive-sided Flycatcher (wood-pewees often show a similar "vested" appearance, and the Olive-sided's diagnostic white patches are usually concealed below other feathers); and to Eastern Phoebe (despite what the field guides say, it needs to be repeated that phoebes often show obvious wing bars and are then mistaken for wood-pewees.
One final word. In case you still want to try to separate silent wood-pewees in the field, consider this sobering account from the Frontiers of Field Identification listserve showing that even specimens can defy identification:
"Two collected Maryland wood-pewee specimens in the Smithsonian [were] considered by some to be Westerns. Morphometrically, we have not been able to separate them from Easterns. At our request, the Smithsonian conducted a DNA analysis. For one specimen the analysis did not work, and for the other the results were 'puzzling' and could possibly involve a 'cryptic species from elsewhere in the range (e.g., the Rocky Mountains)' ".
Well, let's move on to something easier. While it is certainly a stretch to call this group easy, and vocalizations will still provide the most reliable ID criteria, at least there are some useful clues you can usually depend on when confronted with a silent Empid in Minnesota:
• Range and season. Consider where you are and the time of year. During summer and migration, Acadian Flycatchers are to be expected only in the southeastern quarter of the state, and Willows would be rare in northeastern Minnesota. The other three species can occur statewide as migrants. In summer, though, only the Least nests throughout, the Yellow-bellied is limited to the northern counties, while an Alder would be rare south of the Twin Cities and in the southwestern quarter of the state. (Keep in mind, though, that Alders and Yellow-bellieds are often still migrating through southern Minnesota into June.)
• Habitat. In summer, note the habitat. Look for Leasts and Acadians in deciduous woods, Yellow-bellieds are partial to forests with a predominantly coniferous component, while Alders and Willows – true to their names – respectively prefer alder swamps and willow thickets.
• Eye rings. Because of feather wear, eye rings are less prominent on summer/fall adults and on juveniles, but they can be helpful in the ID process. Those on Leasts and Yellow-bellieds are usually the most prominent, and frequently appear "almond" or "tear-drop" shaped; Acadian eye rings tend to be narrower; those on the Alder average even narrower and typically disappear by mid-summer; while a Willow "never" shows an appreciable eye ring.
• Bill size and color. All five Minnesota Empids have relatively broad bills, but you'll often be able to discern that the Least's bill looks shorter than the others. While the lower mandibles on all five are typically entirely pale, the Least would be the only eastern Empid that sometimes shows a dark tip.
• Primary extension. Look at how far the folded primaries extend beyond the tertials. With experience or comparison, the primary extension on Leasts will appear noticeably shorter than on Acadians, Alders, and Willows. (Admittedly, I have no impression of the Yellow-bellied's extension, since I never have much reason to look at it – see below.)
• Plumage. With one exception, to my eye all the eastern Empids look pretty much the same in overall plumage color. But I am usually comfortable telling a silent Yellow-bellied by plumage alone, especially adults in May-June and juveniles: they look especially green above, their wing bars strongly contrast with dark wings, and a grayish "vested" wash underlies the uniform and extensive yellowish tone which continues from throat to under tail coverts (unlike other Empids, which at most show some pale yellow limited to the flanks and under tail coverts).
The above considerations aside, you're always better off if the Empid is singing or even just giving some call notes. There is no need here to describe all their vocalizations, since CDs and internet recordings are easy to find and better than verbal descriptions, but these few comments and transliterations may be helpful:
• Despite what many field guides try to describe, I've never heard an Acadian Flycatcher sing "pizza" or an Alder sing "fee bee o". In reality, Acadians say "peet SEET", accent on the second syllable (not the first, as in the word "pizza"); the Alder's song is burry and two-syllabled, not three: "free beeur".
• Non-singing Empids can often be separated by call notes alone. A flat "whit" narrows it down to a Least or Willow, and Willows also give a distinctive, dry, rising "sprrit". A soft, musical "peep" and a descending, buzzy, siskin-like "shreeur" are both diagnostic of Alder. A loud and sharp "tseet!" indicates an Acadian, while the Yellow-bellied has two unique call notes: a rising, mellow, two-syllabled whistle ("che wee"), and an abrupt, metallic "killink!".
• In addition to their basic and diagnostic call notes, all the Empids can utter other random, multi-syllabled chattering, although I'm unaware if any of that will help you make an ID. And, as pointed out in previous columns, I've twice heard Willows give call notes disturbingly reminiscent of the Alder's "shreeur".
Keep in mind there are six other members of the Empidonax genus in the western U.S.: Hammond's, Gray, Dusky, Pacific-slope, Cordilleran, and Buff-breasted. Although none of these has actually been recorded in Minnesota, any of them could occur here – and perhaps some already have, but were understandably overlooked and undetected. Indeed, I believe all of them except the Buff-breasted have strayed to the eastern U.S.
Their identifications are beyond the scope of this article, but take a second look if you ever see an Empid dipping its tail in the manner of a phoebe, and you just may be looking at a Gray Flycatcher. (But be aware all the Empids can nervously flick their tails and wings, which is different from the Gray's deliberate tail-dipping.) Or, a "Yellow-bellied" flycatcher that's out of season or doesn't quite look or sound right might actually prove to be a Pacific-slope or Cordilleran. And an Empid with a narrow, dark lower mandible is especially worth closer study in case it's a Hammond's, Gray, or Dusky.
A careful, conservative approach to Empidonax identification will always be your best course. and perhaps there's no better cautionary tale than this winter's sighting in Texas of a possible Pine Flycatcher (Empidonax affinis), a species never recorded in the U.S. It's now been around for a couple of months, studied and photographed by dozens of birders (some of them with considerable experience and expertise), and its call notes have been repeatedly recorded and analyzed. The verdict(s) so far, after all this evidence: some still maintain it's a Pine, others confidently claim it's just a Least, and no doubt others with equal conviction have called it something else.
For more complete information on Empidonax identification, I especially recommend the chapter on this genus in Kaufman's A Field Guide to Advanced Birding. There was also an exhaustive five-part series on Empidonax ID in Birding back in the 1980s (Birding 17:151-158, 17:277-287, 18:153-159, 18:315-327, and 19(5):7-15). (I admit it's unlikely that most of you still have 20-year-old copies of this journal lying around, but, remember, mine are for sale!)
Have I mentioned yet that Eastern Phoebes frequently show pewee-like wing bars? Yes, I suppose I have, more than once, but I'm still willing to wager that at least one phoebe will mistakenly be reported as an Eastern Wood-Pewee this April. About the only other confusion I've witnessed involving Eastern Phoebe, especially in Texas, is mistaking a distant, dark-looking Eastern in poor light for a Black Phoebe. But this shouldn't be a problem in Minnesota, since Black Phoebes have demonstrated virtually no vagrancy tendencies to northern or eastern states. (And this is the primary reason why a Minnesota sight record from the 1950s was reluctantly dropped from the state list after decades of debate.)
I haven't seen this happen, but I suppose another source of phoebe confusion could be an Eastern in strong, low-angle sunlight conditions, which might make its underparts appear more rusty than they really are, possibly resulting in an erroneous Say's Phoebe sighting. And, while we're at it, be sure to consult your field guide to understand why birders sometimes confuse female Vermilion Flycatchers with Say's Phoebes. (But what a nice potential "problem" for anyone birding in Minnesota: finding a flycatcher with reddish underparts that's either a Vermilion Flycatcher or Say's Phoebe!)
Like wood-pewees and Empids, much has been written and discussed about the ID problems associated with the flycatchers in this genus. But the situation isn't too complicated here since the only reasonable alternative to Great Crested Flycatcher, Minnesota's default Myiarchus, would be Ash-throated. There are two state records of this flycatcher, both in late fall (consistent with the pattern in other eastern states), so any Great Crested-like flycatcher you see in late October or November naturally deserves special scrutiny. Keep in mind, though, that there are still valid Great Crested records here in late fall, so don't jump too quickly then to the conclusion that you've found a third state record.
Given a decent view, it's not too difficult to separate these two flycatchers, since both the Sibley and Geographic field guides adequately depict their differences in bill color, underparts coloration, and tail feather pattern. But for more complete ID information, one good source would be the account in this journal of Minnesota's first record in 1990 – The Loon 63:4-11.
Eastern Kingbird ID? Hardly a problem here – unless you want to consider the potential for a Gray Kingbird to wander up this way. And, yes, I would consider it, since that species does turn up well north of Florida on occasion. Again, consult your Sibley or Geographic to see the similarities between these two....
....and, while you're at it, also look up the differences in the four yellow kingbirds. So far, all those in Minnesota are Westerns by default, but there is clear potential for the other three species as vagrants. After all, the Cassin's Kingbird is casual in nearby southwestern South Dakota (it has even bred there), and there are several Tropical Kingbird records in northern and eastern states. Couch's Kingbird seems to have less tendency to vagrancy, but there are extralimital records. So, if you're ever lucky enough to turn up an apparent Tropical Kingbird, remember that vocalizations are the only safe way to distinguish one from a Couch's. [Author's Note, August 2016 – There are now confirmed Minnesota records of both Cassin's and Tropical kingbirds.]
Finally, about the only other ID issue I can think of involves two species with some similarities to kingbirds, at least in their posture, behavior, and habitat. Plus, they have long tails that can apparently serve as utensils! The spectacular Scissor-tailed Flycatcher, which appears almost annually in Minnesota, should be a straightforward identification, but it's worth taking a second look, consider the real possibility of Fork-tailed Flycatcher (there are two state records), and be sure to include a sentence or two in your documentation to preclude that species.
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While thumbing through the last issue of The Loon looking for alternatives to writing about flycatchers in winter, I did find an intriguing reference to an unfamiliar species. (Actually, this was pointed out to me by a sharp-eyed reader, which I appreciated, although there was hint of gleeful sarcasm as she related her discovery.) It was on page 167 in the article about loons and grebes, and about all that's known about the species is that it reportedly had "a similar bill shape" to Red-throated Loon. It was called a Yellow-throated Loon (and this typo has since been fixed), and I can only assume its scientific name was Gavia goofii.