A PHOTO DISCUSSION ON NUTTING'S FLYCATCHER IDENTIFICATION:
Part 4: TAIL PATTERN
text © 2003 Don Roberson
all photographs are copyrighted © 2003
by the photographers cited; used here with permission
Lanyon (1961) created a key for separating specimens of Ash-throated and Nutting's Flycatchers, and accompanied that key with two illustrations showing variation in both species. There is remarkable variation is tail pattern. Standard field guides (e.g., National Geographic 1999, Howell & Webb 1995) can only show the most typical patterns. The most important feather is the outermost rectrix, numbered "R6" in banding shorthand (there are six sets of feathers in a flycatcher's tail, thus 12 in all, numbered from the center because the molt is from the center and outward). The shaft of the tail feather separates the tail into two parts: the narrow outer web and the broader inner web. It is the pattern on the inner web that is important.

On most Ash-throated Flycatchers, the inner web is entirely rufous (right up to the shaft) until, near the tip of the feather, the brown outer web suddenly expands and "cuts off" the rufous before it reaches the tail tip. One typical pattern to shown on this fine photograph © Peter LaTourrette, taken at Jasper Ridge near Stanford Univ., California, in April 1993 (many beautiful shots at Jasper Ridge are on Peter's Jasper Ridge web site).

Another common Ash-throated pattern is for this brown color (called "fuscous" by Lanyon) to "hook back" along the inner edge of the inner web, nicely shown (right) on another Peter LaTourrette photo, this one from Stevens Creek park in Santa Clara Co. (yet another wonderful set of photos are on Peter's North American Bird Gallery). 

As we shall see further down this page, the "typical" Nutting's Flycatcher tail does not have the brown outer web rapidly expanded at the tip, "cutting off" the rufous from the tip. Instead, there is a brownish shaft streak, typically including a tiny bit of the inner web next to the shaft, that gradually expands towards the tip. The brown area usually broadens at the tip, but some of the rufous on the inner web is "free" to continue right to the tip of tail. [On both species the thin outer web is mostly brown but in fresh plumage there can be a whitish edge around the entire feather.]

The larger Brown-crested Flycatcher M. tyrannulus apparently has little variation in its tail pattern: a simple shaft streak covering both sides of the shaft, but not expanding at the tip (Cardiff & Dittmann 2000). This pattern is shown in the standard field guides (e.g., Howell & Webb 1995, Nat'l Geographic 1999). In discussing how Brown-crested differs from other Myiarchus, Cardiff & Dittmann (2000) explain that Nutting's is particularly variable in tail pattern, running the gamut from "typical" Brown-crested pattern to (rarely) typical Ash-throated patterns.

Reproduced below is Lanyon's (1961) figures on tail variation in Ash-throated (figure 1) and Nutting's (figure 2) flycatchers. Note the "typical" patterns  of both species come in at least three variations, and then there are "rare" patterns that closely match the pattern of the other species. Lanyon's key shows R6 (the sixth rectrix) on the top row. He also illustrates R2 (the second rectrix) but that is only important when one gets into the "rare" patterns shown by a small minority of birds.

Larry Sansone took the lovely spread-tail shot below of the Orange County, s. California, Nutting's Flycatcher. This or a very similar photo was published at West. Birds 33:193 in the CBRC report that accepted this record. Alas, when we enlarge the tail and number the rectrices, the key feather R6 is half-hidden by branches on both sides in this particular shot.
I have found photos of the Arizona bird, however, that show R6 reasonably well. In the set of three shots below, two of them are of the Arizona bird but by different photographers (Larry Sansone, Ed Harper). Can you pick up the two that are of that Arizona Nutting's? I will tell you that brightness/contrast and hue saturation has been adjusted on one of the shots (but not the others) in an attempt to show the pattern as best as could be done. I am attempting to show R6 on the left hand side, although Lanyon (1961) says his key works with either side and birds are essentially symmetrical in their patterns. That left-hand outer rectrix is labeled "R6." When the tail is folded, this is the bottom feather seen from below.

Can you find the two identical tails in this group? I think it is fairly hard to do because of the differences in lighting , film and reproduction, but the two identical ones are the left-hand and the right-hand birds; only the right-hand bird has been retouched to try to bring out contrast a bit. Note that on all three the rufous inner web extends to the tip at the inside "corner" of the tail tip and for a bit further along the tip. If anything, the center bird seems to have slightly more rufous at the tip. Also, the brown expansion seems a tiny bit more gradual on the Arizona bird (left and right) than the center bird. But on all three you can see that the brown color extends as a thin stripe across the shaft and into the inner web at the mid-point of the tail, about where the words "R6" appear. Tails in this group of Myiarchus run in the 75-95mm range (Lanyon 1961, Pyle 1997) but (of course) some portion is hidden by tail covert feathers where inserted. It is fair to say that the 30-35mm point from the tip is about or just a bit short of the halfway point on the tails. This is the point marked by the double-headed arrows on Lanyon's key (above), and hopefully approximated by the "R6" words on each photo in this set. Obviously, the 20mm point (from the tip) would be about a third closer to the tip. Beyond the pattern of the tail tip, Lanyon explained that the typical Nutting's had a thin but obvious (greater than half-a-millimeter) shaft streak at the 20mm point where the brown encroached into the rufous inner web.

Look for yourself, but I see that there is brown on the inner web, to the right of the feather shaft, at a point a third of the way closer to the tip than the "R6" printing. Indeed, there is still a tiny sliver of brown on the inner web right next to the shaft at the "R6" lettering (or approximately the 30mm mark).

You can see that all these feathers are fresh; none have ragged or worn tips. Therefore the top row of Lanyon's key applies. You can judge for yourself, the patterns shown by these birds (recognizing that the left and right photos are the same bird) seems to generally match "A" in the Nutting's chart (a typical pattern for Nutting's) or, possibly, pattern "E" in the Ash-throated chart (a rare pattern).

The middle photo (above) is the Santa Cruz bird. It is Tom Grey's photo, with tail enlarged, but I have flipped the image to compare it with the other two. It is actually the right-hand R6 (when viewed from below) rather than the left-hand feather. However, Lanyon (1961) says "presence of a character or condition on either the left or right rectrix is acceptable in the use of the key" so comparing a left-hand feather of one bird to the right-hand equivalent feather of the other should not matter. [Again, I repeat that the two left photos above are unadjusted in PhotoShop in any way, except to enlarge the scans.]

However, it is not this simple. Look at the photo immediately to the right, and especially that triangular area outlined in white on the next inset. I see this area as a dull fuscous, and when I first viewed the tail immediately to the right, I thought it was an obvious Ash-throated because the brown covered the entire tip.
I was quite wrong. The tails on the top row just above are all of the Santa Cruz bird, taken at about the same time but with different equipment. Tom Grey's tail (far right, but now reversed to its original orientation) was digiscoped with an Olympus digital camera and a Nikon Fieldscope, and has no flash. Peter LaTourrette's tail (above left) was taken on film with fill-flash.
And, to further complicate things, the bird had just taken a bath. See Peter LaTourrette's photo (just above) of the wet tail see how ragged it looks before it is dried and preened into shape. My own photo of the undertail (just above and far right) is backlit and shows extensive rufous to the inner web extending right to the tip. But I am not convinced we are seeing the pattern of R6 in my shot. The inner rectrices R5 in to R2 have much more rufous on the inner web in each species. If you go back to the photos at the top of this page, you can see how much rufous there was on the inner web of these feathers in the southern California Nutting's. You can see R5 reasonably well even on the wet tail in LaTourrette's photo just above, and it has lots of rufous. If my photo is a composite of R5 and R6, we can't say for sure what the pattern of R6 is in these photos. [We can, however, use field descriptions. Those I have examined, including my own, describe an R6 that has rufous running to the tip, not "cut-off" as in the typical Ash-throated pattern. Thus it would be reasonable to conclude that Tom Grey's digiscoped shot better illustrates the actual pattern than the fill-flash photo by LaTourrette, at least in this specific feature in the early morning lighting present. Fill-flash may have 'created' shadows or color variation where none were present.]

Important Note: These uncertainties about tail pattern illustrate yet again that (a) making subtle color judgments on the basis of one photograph is unwise and (b) differing photographic techniques can yield different results, even if taken contemporaneously.

We also must not overlook the fact that both species (Ash-throated and Nutting's) show extensive variation in tail patterns. Below are some other nice LaTourrette photos of Ash-throated Flycatchers in California. The left hand bird is from Morongo Valley (where Brown-crested also nests) and the center shot is an enlargement of that tail. Below right is the same Santa Clara Co. tail shown near the top of this page. These are just some of the variations present in Ash-throated Flycatcher.


Nutting's Flycatcher, if anything, is even more variable; see Lanyon's chart above. There are various video-caps of the southern California bird that show it had more brown at and near the tip of the tail than did either the Arizona Nutting's or the Santa Cruz bird. My own photograph of that Orange County bird (right) shows extensive dark well into the inner web. [In this unusual shot, R6 is disarranged and sitting unnaturally on the top of the tail, instead of folding below. We thus see the top of the outermost rectrix on the left side. Tail patterns are the same above and below, although the colors may be somewhat more intense from above.]

Given this range of variation, one might opine that the tail pattern of the Santa Cruz bird could fit either species. You can determine for yourself whether it better fits a "typical" pattern of one or the other species, but it may be unwise to assert that the tail pattern conclusively identifies the Santa Cruz bird.

I am particularly grateful to Peter LaTourrette for the photos and points discussed on this page. He says that he has long been skeptical of tail pattern as a very useful character in the field on this group, and the evidence seems to support his comment. The other pages in this project are:

BACK TO NUTTING'S I.D. INTRO PAGE
STRUCTURE
[shape, bill size]
PLUMAGE
[head & belly patterns]
WING PATTERN
[secondary edges, primary projection]
VOCALIZATIONS, MOUTH, ETC
[mouth lining, calls, behavior]
Personal conclusions

LITERATURE CITED:


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