This bird has certainly proven to be a fascinating case study, and the discussion across the various forums has been enlightening. I always appreciate the opportunity to learn from one of these community identification efforts, and I'm grateful for public venues like the listserv where experts can hash out the details in the open air. The specter of hybridization always hangs over discussion of unusual gulls. Documented hybrid swarms like the "Olympic Gulls" of the West Coast illustrate the need for caution when it comes to assigning birds to specific categories. I agree that mixed parentage should be considered with due diligence, but likewise that it should not be the default answer for any individual that is perceived as looking "off." Many of these Larus species, especially the Herring gull complex, are so wildly variable that they can account for many atypical birds even without getting into the muddy waters of hybrids, potential backcrosses, and the like.
The case that has been made for this particular individual being a European Herring Gull is compelling, and this conclusion of this analysis has been backed, at least tentatively, by a few European birders who I've seen chiming in on different gull ID groups. I do wonder if we'll be able to gather enough evidence to surpass the threshold of "acceptability" for such an exceptional record, especially considering that the European taxa are likely candidates for a split (or according to some authorities, already separated at the species level) and thus a potential state record of note. Is there a precedence or protocol for NYSARC treatment of eminently splittable subspecies? If nothing else, I would encourage anyone who is interested and able to continue the collaborative study of this singular individual while it is still with us. As Shai mentioned in previous posts, some of the finer details of soft parts and primary patterns could still serve to be nailed down more conclusively. I did my best to secure useful images during my brief time with the gull this weekend, but I don't think I contributed anything to the records that hadn't already been photographed. Responding to Karlo's point about positively proving the occurrence of European Herring Gulls in eastern North American, a cursory eBird search reveals that many records do seem to be immature individuals. Confidently distinguishing between adults is indeed a prodigious challenge due to the range of variation in the complex, but a yellow-legged, dark-mantled "omissus" bird from the Baltic Sea region might just be the best chance you'd have at satisfactorily doing so. Cheers, -Tim H On Tue, Mar 8, 2022 at 10:31 AM <[email protected]> wrote: > It sure seems that the sightings of the recent Slaty-backed Gull of > Central Park and the interesting yellow-legged Larus of Old Field Point has > sparked some of us to join the ranks of larophiles, especially during the > late winter birding doldrums. I tried doing a little research on American > and European Herring Gulls and find myself even more confused than before. > > According to Lars Svensson in his Birds of Europe, Second Edition (a great > field guide - think of the Nat Geo guides but with many more superb > illustrations and captions per page), the American Herring Gull was > "recently split from Herring Gull on account of distinct first-year plumage > and slight genetic difference. Very similar to Herring Gull, and adults > often inseparable". > > Shai states below that regarding the occurrence of European Herring Gulls > in eastern North America, "the small number of proven cases is not tiny". > I'm wondering how these cases were proven. It seems to me that the only way > to reliably identify an adult European Herring Gull on our shores would be > only if it were a yellow-legged, 'omissus' type. Or you could try sorting > through first-year Herring Gulls - good luck with that! > > Finally, according to the AOU (per Wikipedia), the American Herring Gull > is considered a subspecies of the European Herring Gull. It appears then > that if the consensus on the Old Field Point bird turns out to be European > Herring Gull, it still wouldn't be considered a separate species. > > Karlo Mirth > Forest Hills, NY > > > > > -----Original Message----- > From: Shaibal Mitra <[email protected]> > To: [email protected] <[email protected]>; NYSBIRDS ( > [email protected]) <[email protected]> > Sent: Mon, Mar 7, 2022 10:21 pm > Subject: [nysbirds-l] Is the Old Field Point Bird a Euro Herring Gull or a > Hybrid LBBG x HERG? > > Hi all, > > The breeding biology of Larus gulls is very well studied. Large and noisy, > they often breed abundantly in large, conspicuous colonies where it is > relatively easy to observe their strictly socially-monogamous mating > systems: the members of pairs share elaborate display patterns exclusively > with each other (and not with the members of other pairs) over a period of > many weeks as they cooperate in raising their young. In most places, > whatever the species, the individuals within a colony are very uniform in > appearance, and one almost never observes a pair in which the partners are > of different species, or even where one partner appears intermediate toward > a different species. Over more than forty years watching tens of thousands > of breeding pairs of ten-plus species of gulls and terns, I have only once > witnessed strongly pair-bonded behavior and copulation between individuals > of different species (a Roseate Tern x Common Tern). Among non-breeding > birds, I have found a larger, but still small, nuthat tmber of individuals > that I concluded were likely hybrids (LBBG x HERG, GBBG x HERG, GLGU x > HERG, COTE x ROST). Meanwhile, in the course of being out there on the > outer coast, I have found a considerably larger number of extralimital > gulls and terns of varying degrees of rarity, including some very rare. > I was going to begin this essay with a statement like, “We simply > don’t know how frequently hybridization occurs in Larus gulls”—but this is > insufficient, because we actually DO know how rarely it is observed in most > contexts. Most of what little we know about hybridization in these birds > comes from genetic data revealing that, here and there, the genes of one > species are present in a typical-looking individual of another species, > implying past hybridization (let’s ponder the WEGU that turned out to have > RBGU mtDNA). The rest of what we actually know about it comes from a very > small number of observed hybrid pairings and an even smaller number of > marked offspring of such pairings, whose appearance and behavior were > available for study as they matured and reached adult-hood. > These facts are sufficient to imply that we might expect to see hybrid > Larus from time to time; to support the tentative identification of > intermediate-looking individuals as potential hybrids, and to factor this > possibility into the identification of potential vagrants. After, all Larus > is such a grab-bag of mix and match combinations of leg color, eye color, > mantle color, etc., and also so basically similar ecologically and > anatomically, that appearing intermediate between species A and species B > will often result in resemblance to species C. For instance, the various > taxa of Kelp Gulls were initially described as subspecies of Lesser > Black-backed Gull because they share a combination of color values; > California Gull and Armenian Gull share a combo; Yellow-legged Gull and > omissus-type European Herring Gull share a combo; etc. > The Old Field Point Larus has inspired a lot of interest and at least > a moderate amount of public discussion. I have made what I regard as a > strong case for European Herring Gull because every observable > characteristic of the bird matches trait values that are common in northern > (and possibly eastern) breeding populations of L a. argentatus. This > conclusion has received, in what has reached me so far, a lot of mostly > quiet support and no explicit contradiction. The main obstacle is natural > caution, the perceived improbability of a European Herring Gull appearing > on Long Island, and the perception that hybrid LBBG x HERG are common > enough that one might match this bird’s appearance. I believe the question > of European Herring Gull vs. LBBG x HERG hybrid can be settled with a > reasonable amount of confidence, by a careful logical critique of both > hypotheses. > On the one hand, I hear people say, “It’s reasonable to identify birds > that are intermediate in multiple characters between Herring and Lesser > Black-backed Gulls as hybrids.” And on the other, I’ve heard things like > this, “Given that hybrids are often variable and in some cases are known to > deviate from both parents in some respects, it’s difficult to be sure that > a hybrid could NOT match the appearance of the Old Field Point bird.” Both > these statements (I’ll call them #1 and #2) might sound reasonable, but > they are not. The first should be qualified, “It is reasonable to regard > the birds that are intermediate in multiple characters as likely including > actual hybrids, at least in some cases—and records of such birds should be > studied closely for patterns such as timing, spacing, and unimodality (do > they show a single body of variation or more than one tendency?).” The > second statement is deceiving because it accepts the weaker part, and > abandons the stronger part, of the first: i.e., it assumes that hybrid LBBG > x HERG are common, but it no longer expects them to be intermediate. It > must be remembered that statement 1 is not based on comparing the putative > hybrids with birds of known identity (of which almost none are known); it > is an hypothesis regarding birds of unknown identity, chosen because of > their intermediate appearance. I fully accept that these probably include > actual hybrids, but they also probably include a motley by-catch of > pale-end graellsii (North American LBBGs are oddly variable in mantle > color, so tossing off the pale ones as hybrids is a wrong emboyo), European > Herring Gulls, Yellow-legged Gulls, and hybrids involving completely > different taxa. But even if all of the putative LBBG x HERG hybrids are > really hybrids, they are by no means common. Furthermore, just as we are > probably overstating the frequency of hybrids by lumping in other things, > we are probably NOT over-looking actual hybrids. In closely related species > like these, hybrids are unlikely NOT to be intermediate in general, and > especially in quantitative characters such as size and shape. These > considerations also have implications for statement 2, which must now be > understood as referring to extremes of variation (by definition infrequent) > within an already small number of presumed hybrids. > In contrast, the European Herring Gull hypothesis stands on a > completely different logical basis. First, it is based on comparing the > detailed appearance of the focal bird to large series of birds of known > identity in the northern and eastern breeding populations of L. a. > argentatus. Second, although we do not know how often European Herring > Gulls occur in eastern North America, the small number of proven cases is > not tiny, and surely the actual rate of occurrence greatly exceeds this > number. Adult L. a. argenteus would almost always be overlooked as > smithsonianus—as would adult argentatus with paler mantles and/or pink > legs; darker adults with yellowish legs would be overlooked as hybrids; and > all immatures would be overlooked as Lesser Black-backed Gulls. > The thing that is unusual about Larus is not its supposed promiscuity, > but rather its strong reproductive isolating mechanisms, which allow groups > of local populations to show remarkable phenotypic cohesion, even when they > are very recently isolated and not yet sorted out genetically. In such a > system, where the animals are very closely related, hybrids will be viable > and intermediate in appearance. Thousands of Lesser Black-backed Gulls are > right now migrating north past hundreds of thousands of already-paired-up > Herring Gulls and Great Black backed Gulls. None will drop in and pair with > a HERG or GBBG. Maybe one in a million. No not even that. > > ________________________________________ > > From: Shaibal Mitra > Sent: Monday, February 28, 2022 12:36 PM > To: [email protected]; NYSBIRDS ([email protected]) > Subject: RE: A Long Island, New York Larus with Yellow Legs > > Hi all, > > We studied the yellow-legged Larus at Old Field Point again yesterday, 27 > Feb 2022. For convenience, here are links to some checklists with useful > photos and descriptions of the bird: > > https://ebird.org/atlasny/checklist/S103596988 > https://ebird.org/atlasny/checklist/S103599196 > https://ebird.org/checklist/S103599677 > https://ebird.org/atlasny/checklist/S103711048 > https://ebird.org/checklist/S103758350 > https://ebird.org/checklist/S103798052 > https://ebird.org/atlasny/checklist/S103770855 > https://ebird.org/checklist/S103820434 > https://ebird.org/checklist/S103880419 > > I’m increasingly convinced that this gull is a European L. a. argentatus. > There are many serious obstacles to the alternative interpretations. > > The extent of white on P10 and P9, the restricted amount of black on > PP6-8, the absence of black on P5, and the large size of the apical spots > on all these feathers strongly counter-indicate Lesser Black-backed Gull, > its potential hybrids with various Herring-type taxa, Yellow-legged Gull, > Caspian Gull, and also most “Herring Gulls” (e.g., western/interior North > American L. a. smithsonianus and European L. a. argenteus). These features > of the wingtip are most consistent with northeastern North American > smithsonianus (which is locally abundant) and vagrant argentatus (not yet > documented in New York, but with records from Newfoundland). Published > resources and series of photographs from known sites and dates indicate > that the wingtip pattern wherein these two taxa approach each other most > closely is very similar to that of the Old Field Point bird. There are > several very subtle distinctions in primary pattern between the two taxa, > and the assessment of these in the Old Field Point bird seems to me to be > the primary remaining task (see below). > > But even if this bird’s wingtip pattern is equivocal, it must be noted > that it shows numerous other characters that closely match birds from the > northern breeding areas of L. a. argentatus, and that specifically point > away from L. a. smithsonianus: > > 1. Mantle tone. The bird’s mantle is definitely slightly darker than > in smithsonianus, the pale tone of which is extremely consistent and not > prone to variation (one could examine a thousand breeding Herring Gulls on > Long Island without finding a single bird approaching the mantle tone of > the Old Field Point bird. Conversely, argentatus is darker than > smithsonianus and argenteus, is furthermore described as being variable, > and includes populations described as closely resembling Yellow-legged Gull > in mantle tone (and other features, see next). > 2. Leg color. The bird’s legs and feet are yellow, which is atypical > (but not unknown) for smithsonianus, but quite typical for populations of > argentatus in the northern and eastern parts of its breeding range. Birds > with varying amounts of yellow in the legs and feet occur among > smithsonianus more frequently than do birds with noticeably dark mantles, > but very rarely approach the condition shown by the Old Field Point bird. > in contrast, this feature is common in the very populations of argentatus > that match the Old Field Point bird most closely in terms of wingtip > pattern and mantle color. > 3. Bill pattern. The bill is intensely orange, lacks black markings, > and shows an elongated red gonys spot. The former point is probably > equivocal, as it covaries with leg color in variant smithsonianus: > > https://flic.kr/p/T15pGz > > But the large gonys spot is possibly important, as it definitely points > away from smithsonianus. On Long Island, we are accustomed to interpreting > an elongated red gonys spot as indicative of Lesser Black-backed Gull, and > this was a source of confusion in initial assessments of the present bird. > Interestingly, this feature is apparently not unexpected among those > argentatus that most resemble the OFP bird (dark-mantled, bright-billed, > and restricted black in the wingtip): > > http://www.gull-research.org/hg/hg5cy/adapr47.html > > 4. Orbital ring. The orbital ring appears to be red based on photos > and some descriptions, though I have not been able to confirm this fully to > my own satisfaction. If so, this points strongly away from smithsonianus, > but again, it is expected, in correlation with all the characters discussed > above, among northern argentatus. > > Before concluding with a brief description of our remaining work regarding > the minutiae of the wingtip pattern, I feel the need to emphasize again > that this bird’s resemblance to a hybrid LBBG x HERG in several ways > (mantle tone, leg color, and gonys spot) is nevertheless superficial. For > one thing, the bright yellow leg color is brighter than that observed in > putative hybrids. But more importantly, its overall structure is > Herring-like, and its wingtip pattern is at the extreme end of variation in > smithsonianus, in the direction away from, not toward, the condition in > Lesser Black-backed Gull. > > Here is what remains to be done: > > 5. Nail down the color of the orbital ring and gape. > 6. The shape of the large, broken mirror on P9 is distinctive—what > does it mean? (Example of a similar wingtip and details of p9 from Belgium > 1 Mar: https://macaulaylibrary.org/asset/212753731) > 7. Do the lengths or shapes of the pale tongues in PP7-8 favor either > taxon? > 8. The black band on P6 shows a very slight W shape. This is ascribed > to smithsonianus but is readily found in photos of European Herring Gulls, > at least of ssp. argenteus: > > http://www.gull-research.org/hg/hg5cy/adfeb66.html > > For the sake of thoroughness, these points should be resolved and assessed > with regard to northeastern smithsonianus vs. northern argentatus. But it > seems to me that characters 5-8 could only weakly support smithsonianus or > counter-indicate argentatus, whereas characters 1-3 pose very serious > obstacles for smithsonianus and match northern argentatus to a surprisingly > detailed degree. > > Finally, in going back through my photos of variant Herring and Great > Black-backed Gulls with yellow legs, I found another bird (from 3 May 2014) > that is suggestive of argentatus: > > https://flic.kr/p/RV27qh > > Shai Mitra > Bay Shore > > ________________________________________ > From: Shaibal Mitra > Sent: Thursday, February 24, 2022 8:47 AM > To: [email protected]; NYSBIRDS ([email protected]) > Subject: A Long Island, New York Larus with Yellow Legs > > Dear ID Frontiers NYSBirds, > > I would appreciate feedback regarding an adult yellow-legged Larus found > 22 Feb at Old Field Point, on the north shore of central Long Island, New > York. > > Broadly speaking, it is a Herring Gull type, but there are reasons to > doubt each of the usual (and less usual) interpretations of Herring-like > gulls with yellow legs in this region at this time of year. > > Most often, such birds prove to be otherwise typical smithsonianus Herring > Herring Gulls, which regularly show some degree of yellow color in the legs > and feet in late winter and early spring (as do small numbers of local > Great Black-backed Gulls). Another frequent interpretation is Herring Gull > x Lesser Black-backed Gull hybrid, which the original finder, Patrice > Domeischel, considered in the present case because of the bird's slightly > darker than smithsonianus mantle. A third possibility, always present in > the minds of New York gull aficionados, is Yellow-legged Gull, which was > considered by Patrice, and also by Peter Osswald, who independently found > the bird on 23 Feb. > > Patricia Lindsay and I studied the bird yesterday afternoon (23 Feb), and > I have reservations about all three of these hypotheses, which are > explained in my eBird report (link below). Briefly, Yellow-legged Gull is > counter-indicated by this bird's heavier than expected head and nape > streaking; it's notably large (larger than typical smithsonianus) apical > spots on the primaries; and other details of the wingtip pattern (more > white, less black than typical for smithsonianus, let along Yellow-legged > Gull). The latter two points regarding the primaries also point away from > Lesser Black-backed Gull ancestry. Finally, American Herring Gull is > problematic by virtue of the subtly (but clearly) darker than typical > mantle tone; the completely clear yellow tones of the the legs and feet; > and details of the wingtip pattern. I could not see the orbital ring color. > Photos by Patrice and Barbara Lagois seem to show it is red, but are not > decisive on this point, in my opinion. > > I wonder if this bird might represent a yellow-legged example of northern > European L. a. argentatus, which I do not know well in life, but which is > described as having a slightly darker mantle tone than smithsonianus, a > wingtip pattern very similar to the present bird, and a relatively high > incidence of yellow leg color. > > My preliminary analysis (with photos by Barbara Lagois) and two of > Patrice's checklists, also with excellent photos can be found here: > > https://ebird.org/checklist/S103599677 > https://ebird.org/atlasny/checklist/S103599196 > https://ebird.org/atlasny/checklist/S103596988 > > Shai Mitra > Bay Shore, New York > > -- > > NYSbirds-L List Info: > http://www.NortheastBirding.com/NYSbirdsWELCOME.htm > <http://www.northeastbirding.com/NYSbirdsWELCOME.htm> > http://www.NortheastBirding.com/NYSbirdsRULES.htm > <http://www.northeastbirding.com/NYSbirdsRULES.htm> > http://www.NortheastBirding.com/NYSbirdsSubscribeConfigurationLeave.htm > <http://www.northeastbirding.com/NYSbirdsSubscribeConfigurationLeave.htm> > > ARCHIVES: > 1) http://www.mail-archive.com/[email protected]/maillist.html > 2) http://www.surfbirds.com/birdingmail/Group/NYSBirds-L > 3) http://birding.aba.org/maillist/NY01 > > Please submit your observations to eBird: > http://ebird.org/content/ebird/ > > -- > > -- > *NYSbirds-L List Info:* > Welcome and Basics <http://www.northeastbirding.com/NYSbirdsWELCOME.htm> > Rules and Information <http://www.northeastbirding.com/NYSbirdsRULES.htm> > Subscribe, Configuration and Leave > <http://www.northeastbirding.com/NYSbirdsSubscribeConfigurationLeave.htm> > *Archives:* > The Mail Archive > <http://www.mail-archive.com/[email protected]/maillist.html> > Surfbirds <http://www.surfbirds.com/birdingmail/Group/NYSBirds-L> > ABA <http://birding.aba.org/maillist/NY01> > *Please submit your observations to **eBird* > <http://ebird.org/content/ebird/>*!* > -- > -- NYSbirds-L List Info: http://www.NortheastBirding.com/NYSbirdsWELCOME.htm http://www.NortheastBirding.com/NYSbirdsRULES.htm http://www.NortheastBirding.com/NYSbirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/[email protected]/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/NYSBirds-L 3) http://birding.aba.org/maillist/NY01 Please submit your observations to eBird: http://ebird.org/content/ebird/ --
