In the preceding set of pages, I have laid out a lot of evidence and sorted through a lot of literature, trying to present things of importance but permitting the reader to make his or her own evaluations of that evidence. I strongly suspect, however, that my opinion is nonetheless obvious at various points. This is a source of bias, and should be addressed before going on to my personal thoughts about the identity of this Santa Cruz bird.
BIAS: As one of those initially identifying this bird as a Nutting's, it can fairly be said that I am now biased in favor of Nutting's. I did not have this bias, however, when going up to look for it. At that point I was neutral about identification, understanding only that there was an interesting Myiarchus that had points against Dusky-capped and had some features described that sounded to me like Nutting's (no one suggested it was a Nutting's to me initially). Even at that, it is fair to say that I have a bias toward the concept that well-seen birds can be identified in the field, but often only with appropriate field or museum experience, or after literature research.
I think it is also fair to say that there are a set of keen birdwatchers, often with an ornithological background, who come with a bias that some birds cannot be identified in the field. This comes from various sources — for some it is a strong preference for specimen evidence1 or those jaded by mistaken field claims in the past (the late Allan Philips was among those; his disciples follow some of these footprints), for others it is a philosophical approach that it is the process that is interesting, not the end result (they tend to say things like "why do we have to put this is a particular box?" or "I prefer to leave this unresolved"). I think it is fair to call them 'conservatives.' There is another field-oriented set who are confident about their field skills and feel they can identify most anything. Perhaps we could call them 'liberals'. I prefer to think of myself more in the middle — with my mug on one side looking at the bird, and my rump on the other side, bogged down in the literature and museum research — a 'mugwump', if you will (a good old-fashioned political term from the 1870s). It is also fair to say that I come from a legal background, where one marshals evidence to argue for a particular result, and generally believes that one can reach a conclusion. These biases will undoubtedly appear throughout these pages. You will find some bias in almost anyone in the scale of liberals to conservatives when it comes to reviewing bird records.
I believe that science is best served by reviewing the evidence available and drawing the conclusion (i.e., the identification) best supported by the evidence. Ornithologists do this all the time in other ways. The taxonomic order of birds on the A.O.U. Check-List, or any checklist, is simply a hypothesis, based on the best evidence at the time, of the relationships of the birds listed there. Hardly an issue of an ornithological journal appears without new evidence that could affect the order of the checklist, sometimes dramatically. Yet, we do not avoid making checklists because we don't have "all the evidence." We will never have "all the evidence." We can only work with the evidence currently available. If more evidence is developed later, great! We can change our conclusions at that time. But I do not see the fact that additional evidence may come to light as a reason to leave a bird unidentified when, giving proper weight to that evidence, we can reach a current conclusion that is consistent with the evidence. If my evaluation (below) is wrong and new evidence supports a different conclusion, I will simple revise my evaluation at that time, just as we revise our checklist order from time to time.
PERSONAL EVALUATION: Notwithstanding the elements of bias, and recognizing that this is the least important of this set of pages, here is my analysis of the Santa Cruz flycatcher:
|One cannot adequately evaluate size from photos, although in the field I always felt it was small and dainty, rather than mid-sized and rangy like Ash-throated. To my eye the Santa Cruz bird is a very good match in shape to the s. Calif. & Arizona Nutting's, and lacks the long wings of Ash-throated. Most importantly, although there is overlap in bill lengths, this bird was not only short-billed but thick-billed and broad-billed at its base. This is entirely consistent with Nutting's, and would be a very odd Ash-throated, indeed. These features favor Nutting's. The pink color at the gape and base of lower mandible is also consistent with Nutting's, and rather rare in Ash-throated.|
|Another set of characters impossible to evaluate on photos. Lighting conditions and film type (or the character of the scope in digiscoped images) are critical. All photos in the sun wash out the color saturation. The particular photo (right; © D. Roberson) is a good match to what I saw in the field: rather darkish gray breast well separated from yellow belly, and contrastingly dark auriculars. Also no gray nuchal collar. These are consistent points with Nutting's but, given the difficulty in photo review and even in field observations without comparative material, Ash-throated cannot be ruled out on these points. Reviewers can pick a number of photos to try to show the opposite of my evaluation. Perhaps this should be called "neutral" although I feel that the auricular/throat contrast in particular favors Nutting's. [The rusty-edged uppertail coverts are consistent with Nutting's, and may favor it significantly, but more evidence is needed.]|
|In the field I saw rufous inner webs extending to the tip of R6, and I believe that this is shown by the photos on my "tail pattern" page in this series. Although there is a broadening of the brown at the tip, it is comparatively gradual. In this view (© Tom Grey) of the wet tail from above, this pattern may be even more obvious. I easily see this as within pattern 2A in Lanyon (1961), a typical Nutting's pattern. It can also be matched by pattern 1E, a rare Ash-throated pattern. While I feel that the tail is quite typical for a Nutting's, it also does not rule out Ash-throated, so the character is evaluated "neutral."|
|In the field, I saw the inside of the upper mandible as orange. In this photo is looks bright pink to my eye, but we saw that the color picker chose a maroon. In any event, it is a bright color. In no way is it "flesh" or "dull yellowish" as is typical of Ash-throated. Those claiming to see a dull color in the field may have seen the inside of the lower mandible. So, again, the mouth lining to me was typical of Nutting's but, as detailed on another page, this character may be subject to age-related variation. Thus it is not conclusive; rather, this character simply favors Nutting's.|
|It seems hopeless to sort between written renditions of vocalizations
by different observers. Yet, between hundreds of calls over weeks of observation,
the bird never gave any typical Ash-throated calls. It's 'standard' call
was whistled, short, and sharp — I said whik! and others used other
words (pweep, etc.). Even one who thought the calls could match
Ash-throated agreed it was a whistled wip!.The two observers spending
the most time eventually heard longer, upslurred wheet calls, said
to be diagnostic of Nutting's. I did not hear those, but those I did hear
seemed well outside my experience with Ash-throated. I judge the calls
as likely diagnostic, but obvious that is simply a personal opinion.
As to behavior, its olive-eating habits were consistent with what we know of Nutting's and inconsistent with many Ash-throats. Doesn't rule out Ash-throated, but favors Nutting's to some extent.
|Useful only if one knows the age of the bird in question. Birds with retained juvenal secondaries, like many vagrant Myiarchus eastward in fall, cannot be identified by wing pattern. Those birds have first-basic tails (molted on summer grounds) but retained juvenal outer secondaries (molt suspended during migration). Fortunately, we know that the Santa Cruz bird is in first basic plumage because there is a retained mid-secondary (S5) but we can see very fresh round-tipped outer secondaries (S1-S4). We can see these without dispute only because of the high quality digital photos by Kevin McKereghan. Field notes were inadequate to provide anything more than a suggestion of the important points. In the field I saw the 'mid-panel' as "lemon yellow" (meaning "pale yellow") and they appear that way in film photos in natural light. This color is washed out in McKereghan's photo but I believe it is indisputable that the edges of S2-S4 are the same color as the belly in his shots. McKereghan's photos are superb for details but demonstrably washed out on color saturation.|
|Other photos (like Tom Grey's digiscoped image, near right) show the panel as more cinnamon, but this is also a photographic artifact. The color was not this rusty; at most it looked pale yellow on S2-4 in the field. When I blow up the McKereghan photo to an extreme (far right), these feathers have a complex tri-colored pattern of whitish, pale tan, and fuscous. A secondary "mid-panel" that grades from rufous to orange (=cinnamon) to pale yellow or pale tan is the classic Nutting's pattern according to Lanyon (1961). There is not evidence it can ever be shown in post-juvenal Ash-throats. Even texts that suggest there can be a yellowish tone to secondary edges in Ash-throated (e.g., Howell & Webb 1994, 1995) do not claim that S1 can ever be deep rufous in Ash-throated.|
|It is that outermost secondary (S1) that is critical on a known-age bird. The fresh outermost secondary (S1) of the Santa Cruz bird had an extensively deep rufous edge, very similar in color to the deep rufous edges of the inner primaries. The next secondary (S2) has a rufous-edged base and quickly becomes more orange-yellow. According to Lanyon (1961), these points eliminate first-basic Ash-throated entirely. Recall that Lanyon (1961) considered the secondary pattern useful in late fall because the colors faded in winter. In the freshest late fall Ash-throated, the S1 edge is normally white or, at most, "pale rufous." In contrast, he says the Nutting's S1 is always deep rufous. By January, any "pale rufous" on S1 of Ash-throated would be faded considerably (to something like whitish) and recall that the vast majority of Ash-throated have S1 edges that are white from their inception. There is no evidence to suggest that Ash-throated ever has a first-basic S1 with an extensive deep rufous edge, closely matching the color of P1's edge, like McKereghan's photo (right) shows.|
BOTTOM LINE: There is no character on this bird that favors Ash-throated. Every point is either neutral or favors typical Nutting's. Such an accumulation of evidence strongly supports the identification as Nutting's. Perhaps most important, the combination of the bill size and shape, plus the wing panel character , and specifically the deep rufous color throughout the edge of S1, tips the identification into the "positive" category. The calls are consistent, and those heard by others are apparently diagnostic. I believe that the bird is a Nutting's Flycatcher.
I have seen reviews that considered this bird an Ash-throated. I believe them to rely much too heavily on single photos, and particularly they rely on the McKereghan photos — not for the rufous-edged S1 that those reviewers mostly ignore — but for claims that S2-4 were white (like Ash-throated), and that the auriculars are gray (like Ash-throated, but ignoring the contrast shown). McKereghan's shots are wonderful and are, indeed, the key to the whole puzzle, but they do not show true color saturation. They show detail. Even at that, when properly used, they show the edges of S2-4 to be pale yellow (per the color picker) to a tri-colored pattern of white, pale tan, and fuscous (extreme close-up). Either color statement is consistent with the gradually changing 'mid-panel' pattern of Nutting's.
Other negative reviews have relied on "retranslation" of calls (i.e., they read into the details a whit-like call, even though no one heard a soft, lazy whit). It seems probable, however, that some of the soft short calls of Nutting's cannot be separated from some soft short calls of Ash-throated. It is the quality of the louder, sharper calls that are more important. Those calls I described included exclamation points to emphasize sharpness and upslurred energy. Some have relied on evidence of "flesh-colored" mouth linings, but, as demonstrated, all the photographic evidence is of bright colors on the mouth linings (a Nutting's feature) and dull colors inside the lower mandible (a feature shared by both species). Typically "orange" mouth linings were seen by many in the field.
This is a particularly interesting Nutting's because it is a first-year bird, rather than an adult as were the southern California and Arizona birds. I believe we can learn from this bird. Hypotheses supported by this bird include:
All of these preceding pages were written in February 2003. A few people have asked if my personal opinion has changed given the new information now available on Joe Morlan's web site, and especially given his September 2003 statement: "I believe the recordings and sonograms provide compelling evidence that this bird was an Ash-throated Flycatcher." The short answer to whether this changes my opinion is "no." A more expansive response follows.
|The video-tape and songogram:
All that is "new" is that a videotape which included the standard soft call of the Santa Cruz bird has been digitized and sonogramed. This is the call written variously as qwip, pwik, or wip! and was given hundreds of times each day. I have personally reviewed the videotape; this is the only call on the tape. None of the alternate calls heard during the bird's stay is on the tape.
In the preceding discussion, we have already seen (through a literature review) that it appears all four Myiarchus have a soft wit-like call. My conclusion on this topic in February was "It seems probable, however, that some of the soft short calls of Nutting's cannot be separated from some soft short calls of Ash-throated." In other words, nothing about this soft call was going to get us very far.
Since February, Joe Morlan has added various sound cuts to his web page discussion, including the soft wit call of Ash-throated from a wintering bird in Mexico and recorded by Alvaro Jaramillo. Also included are two cuts of Nutting's from Mexico. Both are of birds interacting with another Myiarchus and are possibly the calls of interacting pairs. There is no cut of a single soft-calling Nutting's. However, I pointed out that one of the Nutting's cuts includes two introductory notes that are rather like soft wit-like calls. These are not "stand-alone" notes and may or may not be similar to the pit note described by Lanyon for Nutting's.
I have reviewed the video-tape of the Santa Cruz bird with the Mexico cuts of both species. There is a strong similarity between the Santa Cruz bird's soft call and the winter Ash-throated, but to my ear it was not identical. I disagree with Joe's June statement that "To me, the vocalizations sound exactly like the winter-calls of Ash-throated Flycatcher on my reference page." Rather, I think they are very similar but not that different in quality from the soft wit-like calls that are the introductory notes in one set of Nutting's, excepting, of course, that the Nutting's tape is a lot louder in intensity as the calls are introductory notes that then go into a vigorous set of other calls.
The new songogram evidence compares the Santa Cruz soft call with the winter Ash-throated and the two softer introductory notes of the Nutting's cuts. I emphasize again, however, that there is no comparison at all with a soft-calling lone Nutting's. Rather, the two introductory notes on that cut of Nutting's otherwise includes much more vigorous calls, and all cuts of Nutting's calls are of birds vocalizing in response to another Myiarchus. The Nutting's cut is substantially louder in volume/amplitude than the Ash-throated or the Santa Cruz cut.
I do not have much training in reading sonograms but I see in this comparison that none of the cuts are "identical" to any other. The cuts of Santa Cruz and Ash-throated are most similar to each other but the difference from the Nutting's "soft call" looks to me to be primarily one of amplitude (intensity = loudness) and not of structure. Morlan includes the wheep call of Nutting's for comparison, but no one ever suggested that the Santa Cruz soft call was the loud wheep note, so its inclusion in the set only serves to bias the comparison. He should have included the ka-brick of Ash-throated in the series to equalize the comparative choices.
So at the end of the whole effort (which is appreciated) we are left pretty much at the same place where we were last February. The Santa Cruz soft call might well be matched by Ash-throated and might well be matched by Nutting's. We now have firmer evidence it matches Ash-throated but we lack any firm evidence that it does not match the soft pit call of Nutting's. We have no lone soft-calling Nutting's example to make that comparison. I still suspect that the soft wit-like calls of all four species are close enough that identification on that point alone will always be insufficient. No evidence to the contrary has yet been presented.
In addition to all this, the sample sizes used for this "new" conclusion are incredibly small. A sample size of Ash-throated is one (1) winter bird. The sample size of Nutting's is zero (0) lone calling birds, and one (1) Nutting's with two introductory notes that may or may not be an example to the pit call. In short, this "new" evidence is, perhaps, much ado about nothing.
In March 2003, Joe Morlan and Dan Singer reviewed specimens at the California Academy of Sciences. Morlan has usefully summarized their findings on-line, and I quote a bit of them here, with Morlan's comments in italics and my thoughts in regular type:
Morlan wrote: Lanyon's statement about the difference in the amount of rust on s1 is not supported by our specimen research. The secondary pattern shown by the Santa Cruz bird seemed more consistent with Ash-throated Flycatcher. However, it was also consistent with Lanyon's descriptions of Nutting's and perhaps a larger collection of Nutting's would show more variation.
I am unable to evaluate this finding because I have yet to visit a museum with sufficient resources. I am a bit skeptical about this finding, and I note that Joe admits that another and larger series might support Lanyon's research. Lanyon's work was with a much larger series of specimens than the rather small series of winter birds at CAS. However, the Morlan/Singer finding does call into question the usefulness of the s1 edging character that I had previously emphasized.
Morlan wrote: In my opinion, the size and shape of the bill of the Santa Cruz bird is consistent with Nutting's, and not Ash-throated. The chest pattern, nape pattern, and rump color seemed to me to be better for Nutting's, but it is difficult to draw firm conclusions from the specimens we examined.
These conclusions are the same as I reached through an analysis of photos in the preceding pages. Joe and Dan did not look at primary extension in specimens for reasons described on Joe's site, but that is also another compelling pro-Nutting's feature. Joe's site does have some color photos of specimens that suggest that the uppertail covert/rump pattern may be a stronger pro-Nutting's feature than previously known. In other words, excepting only the questioning of the s1 pattern are a good pro-Nutting's character, the museum research generally supported the idea that the Santa Cruz bird was a Nutting's.
Morlan wrote: The most compelling argument for Nutting's remains the voice. [emphasis added]
Since I know that neither Joe nor I thought the soft wit-like call was diagnostic last winter, I can only presume from this March statement that Joe was relying on the following information, quoted here from his web site (emphasis added):
Morlan now (16 Sep 2003) says: "I believe the sonograms show the vocalizations are consistent with Ash-throated Flycatcher and inconsistent with Nutting's including the soft calls of Nutting's."
For reasons set out above, I think this statement is well outside the bounds of the available evidence. It is possible that it is a true statement, and if it were shown to be true my conclusions would indeed change, but currently the evidence does not support this strong conclusion. Without an adequate sample of Nutting's, the fact that tapes of the soft calls of the Santa Cruz bird are similar to soft calls of winter Ash-throated does not rule out the possibility that they may also be similar to the soft calls of non-paired Nutting's. There is simply inadequate evidence to make this determination.
This new statement also entirely ignores the range of variation and the other calls documented by Santa Cruz birders. I think that primary emphasis on an ambiguous soft call that can probably be matched by either species is unwarranted.
It is still my opinion that the bill size and shape, plumage patterns on face and chest, uppertail covert/rump color, short primary projection, mouth lining color, behavior, and classic Nutting's tail pattern all strongly suggest that the Santa Cruz bird was a Nutting's, and that its soft call was inconclusive as within the category of calls apparently shared by all Myiarchus of this set. I also note again that local observers who spent much more time with the bird than anyone else never heard "standard" Ash-throated calls and, instead, heard loud calls that are consistent with the diagnostic notes of Nutting's.
As has been the case with some past records of difficult birds, this Santa Cruz record has now taken on a life of its own, and much of the current climate may be associated with birding politics and various peer pressures. The California Bird Records Committee is purposefully constructed to be conservative [i.e., it takes only 2 of 10 votes to reject a record] and there is little doubt that the claim of Nutting's will not be accepted. You can expect to find this listed as a "rejected" record in due course.
This does not necessarily mean anything. The Committee has been wrong in the past and will be wrong again in the future. Sometimes they re-review a record a decade later and correct a mistaken conclusion; sometimes they do not. There is a certain randomness to these things.
It may be that additional evidence will add to our understanding of this bird. It is possible that it could return this next winter and be trapped and examined in-hand. This may prove conclusive one way or the other. Likewise, it is possible that it could return and that other calls would be captured on tape, and that they would be conclusive. It does not seem to me, however, that an analysis of the "soft" call will be of that much value absent a much better understanding of the range of calls given by Nutting's.
It is also possible that future experiences with a different bird, or a more lengthy museum project, will prove or disprove the usefulness of features such as bill shape, primary projection, s1 pattern, and uppertail covert/rump color, and shed further light on this Santa Cruz individual.
I strongly recommend that each of you review the evidence for yourself, and reach your own conclusion. This bird is particularly interesting because there is a lot of physical evidence that each of you can review. You have before you, either on this site or Joe Morlan's site, a good chunk of the information that will be reviewed by the CBRC and others. You need not necessarily rely on the opinion of anyone else.
— comments of D. Roberson
24 Sep 2003
All in all, a very interesting bird. I would again like to thank all the photographers who contributed photographs, the observers who provided field descriptions, and those who commented on draft pages of this project, especially Rita Carratello, Steve Gerow, Tom Grey, Bill Hill, Peter LaTourrette, Joe Morlan, Dan Singer, and David Suddjian.
The earlier pages in this project are:
[shape, bill size]
[head & belly patterns]
[secondary edges, primary projection]
[mouth lining, calls, behavior]
1 As described in the introduction of my book Monterey Birds 2d ed. (2002), there is much important information that can be learned only from specimens, and I support the appropriate collection of scientific specimens. Much of my published research includes specimen analysis. However, I do not believe that collecting a vagrant bird to determine its identification is an appropriate type of specimen collection. I believe that in virtually every case, we can identify the bird without shooting it. Indeed, much information is lost when the bird is dead (e.g., vocal & behavioral information) and then we foreclose answering other interesting questions, such as "will it return next winter" and, if so, "for how many winters"? [A good example is the Pt. Reyes skylark whose identification was first thought intractable without a specimen, but proved to be identifiable with adequate evidence, and eventually returned for six consecutive winters]. I would strongly oppose collecting the Santa Cruz bird, for example, but netting it for weights and measurements could be very useful.LITERATURE CITED:
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