While searching the gull flock at the river mouth of Doheny State Beach,
I discovered a very pale, very delicate larid that I felt had the classic
characteristics of a first-winter Larus (glaucoides) kumlieni. I
recognized that such a claim would be controversial, given the lack of
any accepted California record and the uncertainty about the taxonomy and
limits of this form and L. thayeri, yet I felt that the individual
was interesting enough to report to local birders, the local rare bird
alert, and the southern California bird box. I did take a half-roll of
photos with my 500mm lens but the bird was still fairly distant across
the river channel from me. Fortunately, I happened to have Kodachrome 64
in the camera so the photo grain is not too bad. The first photo below
shows the pale first-winter gull among a line of (mostly) California Gulls
californicus, and shows its general size was similar to that species
(in other words, a very small 4-year gull).
The next photo (above left) illustrates the delicate appearance of the bird with a very small, delicate bill (possibly this suggests a female if the variation shown in Grant 1986 is typical?), and the comparatively long-winged & short-legged appearance (this photo was under-exposed and was brightened in PhotoShop by Joe Morlan; the others are published untouched). The following shot (above right) tries to bring out more detail in the tertials, as well as the general "checkered" pattern to the coverts, scapulars, and back. The heaviest barred feature were the undertail coverts. In the field the tertial pattern was quite dramatic, being essentially white with a then pale brown bar down the shaft and various short bars or squiggles radiating outward. The overall impression was of lightly-barred tertials; none had a solidly-colored center of any type. I did not note any secondary bar when it briefly stretched, but perhaps the secondaries are a bit darker than the primaries and the bird would show a slight secondary bar in flight. The primaries themselves were mocha with broad white edges. It was this pattern that led me to believe this was a mid-range "Kumlien's" type, not an extreme pale end approaching nominate glaucoides as have appeared on a couple prior California records.
My final shot (lower left) shows the bird preening its spread tail. In the field I sketched an all-white tail with a broad whitish tip and then a series of thin tan bands across it, totally lacking any "tail band" effect. I believe that the photograph confirms my field sketch.
DISCUSSION: I had previously been familiar with the literature on this taxa and that on Thayer's Gull. Of particular importance are Lehman (1980), Grant (1986), Zimmer (1990), and Zimmer (1991). Therefore I paid particular attention to the tertials and tail. I also noted the overall frosty-white coloration, the lack of a darkish eye patch, and the apparently all-black bill.
I am also very familiar with Thayer's Gull and its variations, as it is reasonably common along the Monterey County coast where I live, and especially so at favored roosting sites at the Little Sur R. mouth and in Moss Landing harbor. In recent years I have routinely assigned crisp first-winter birds to "dark-end," "typical," and "pale-end" subsets of Thayer's (and have squelched various local claims of "Iceland" that were just "pale-end" Thayer's). The photo on the cover of Birding magazine for December 1980 is a fine photo of a "pale-end" first-winter Thayer's.
Given my experience, I have rarely seen a bird of this group as small and delicate as this one. Zimmer (1990, 1991) suggests this is more characteristic of Kumlien's than Thayer's. I have only twice seen first-winter individual which were this frosty-pale: a white-winged bird at the Otay dump, San Diego, in Jan 1986 (a photo is on the CBRC web site here) which was presumably the extreme white end of kumlieni as it had nominate-like all-white primaries, and a more "mid-range" kumlieni type at Moss Landing harbor in mid-Feb 1998. Both birds have been submitted to the CBRC as "Iceland Gulls" outside the range of Thayer's Gull. I posted a description of the Moss Landing bird on the Internet last winter; the strong majority of correspondents from the East Coast felt it was well within the range of the Icelands they see there.
Of course it is the variability of Thayer's Gull that causes the problem;
the potential that they may be the same species (within a biological concept)
doesn't help matters. Lehman (1980) and Zimmer (1991) suggest that the
key points may be: (1) tertial pattern, (2) primary color, (3) secondary
bar, and (4) tail pattern. In addition, size & shape and the presence
or absence of an dusky eyepatch may be useful. On these latter features,
the Doheny bird is consistent with Iceland. On the four specific features:
Tertials: Thayer's have solidly-colored dark-centered tertials fringed in pale. Those of Kumlien's Iceland are variable but "typical" birds have tertials that are mostly white with bars or squiggles. The Doheny bird was a classic Kumlien's on this feature and outside the range of any Thayer's I've ever seen (in life or in photos). Zimmer (1991) says that "a minority of Thayer's will have significant internal pale markings in the tertials but will still show at least a reduced panel of solid brown somewhere in the bunched feather group." The Doheny bird lacked any solid brown panel.
Primaries: the bird is question had primaries that were basically the same color as the body, well within the pattern shown in Zimmer (1991) for the vast majority of first-winter Kumlien's and paler than the palest-end Thayer's in my experience.
Secondaries: I didn't see a secondary bar nor is it apparent in the photos, but Matt Heindel has posted a description that states the secondaries were darker than the primaries, and that it is likely a secondary bar would be present in flight (he did not see it fly). Even accepting his description as accurate, such a secondary bar would have been less than prominent. Zimmer (1990) thought presence or absence of a secondary bar was an important feature (because Thayer's certainly has a strong one; see Lehman 1980) but after further research Zimmer (1991) stated: "At least some Icelands do have a pale secondary bar, although it may be apparent only under good viewing conditions." That this bird may have a pale secondary bar, then, is a neutral feature (not a negative feature for Iceland).
Tail: First-winter Thayer's Gulls -- at all ends of the spectrum -- have a distal tail band (Lehman 1980, Grant 1986). Zimmer (1991) goes to great lengths to show that most Kumlien's also have a tail band. He states:
"My field experience indicates that the majority of birds have a true band, with an many as 15 to 20 percent lacking one. Bruce Mactavish of Newfoundland, who has few peers when it comes to field experience with kumlieni, places the number of birds lacking a tail band much lower, at 5 percent or less. No doubt part of the discrepancy is explained by the way in which birds with intermediate patterns are categorized."No doubt this is true. However, I would categorize the Doheny bird as lacking any "tail band" (i.e., no solid broad band of dark color at the distal end of the tail) but having rather a whitish tail marked with a series of thin tannish bands. If my analysis is right, this places the Doheny bird well outside the range of thayeri and into the small percentage of pale-end kumlieni that show this pattern.
While I recognize that some have recently been promoting the idea that it may be impossible to distinguish between these taxa, and while I accept that as true for some subset of these gulls, I continue to find evidence that those gulls at the ends of cline are identifiable. Say what you will, I am inclined to believe that a very small, very pale first-winter bird of this group which has white, lightly-barred tertials; mochoa-colored primaries; and lacks a tail band is well outside the known range of Thayer's Gull. The fact that all other features considered are either consistent with this hypothesis, or neutral, is also helpful.
Grant, P. J. 1986. Gulls: an Identification Guide. 2d ed. T.
& A.D. Poyser, Stratfordshire, England, and Buteo Books, Vermillion,
Lehman, P. E. 1980. The identification of Thayer's Gull in the field. Birding 12: 198-210.
Zimmer, K. J. 1990. "The Thayer's Gull complex," pp. 114-130 in Field Guide to Advanced Birding by K. Kaufman. Houghton Mifflin, Boston.
Zimmer, K. J. 1991. Plumage variation in "Kumlien's" Iceland Gull. Birding 23: 254-269.
UPDATE Dec 1999
Additional photos of this bird by Matt Heindel are posted on Joe Morlan's web site (find the "Iceland Gull" 19 Feb 1999 to bring up photos) and links to his discussion. After I posted this page, I corresponded with a variety of expert gull-watchers on both sides of the Atlantic. All those with experience with "Kumlien's" Gull who expressed opinions to me stated that this particular bird was well within the typical range of first-year birds they see.
The CBRC reviewed this record and rejected it, presumably influenced by the arguments of Matt Heindel to which you are directed above. It is my understanding of their argument is that they want an acceptable California record of this taxon to show all white wings, no hint of tail band, essentially white tertials, and no secondary bar (this may be somewhat simplified, but is generally their approach; it appears that the tiny size, bill size, and crisp frosty plumage was not considered important). Because this ORA bird had somewhat mottled barred tertials, a hint of tail band (apparent in some photos more than others) and a slight secondary bar, this bird did not fit their criteria. It is my opinion that this is an extreme approach, based more on philosophy than reality, and excludes a good chunk of the "typical" Iceland Gulls seen in northeast North America, as detailed in the discussion above. It also results in the rather odd situation in which there are raity-committee-accepted records of this taxon across the Great Plains, in Texas, in the northwest (B.C. to Oregon) but apparently such birds "do not occur" in California. [There are additional extreme-pale-end claims of Iceland Gull still under CBRC review; it is still possible one or more of those will be accepted.]
Apparently this is the current approach. I still feel that this Doheny Beach bird was a rather mainstream "Kumlien's" based on the input I had from eastern & European observers, but it does not fit into the extreme pale end of cline, so it stands rejected.
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