The mysterious yellow-legged Larus just flew in and is currently preening on the beach at Old Field Point.
Cheers, -Tim H > On Feb 28, 2022, at 12:37 PM, Shaibal Mitra <shaibal.mi...@csi.cuny.edu> > wrote: > > 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: birdw...@listserv.ksu.edu; NYSBIRDS (NYSBIRDS-L@cornell.edu) > 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/NYSbirdsRULES.htm > http://www.NortheastBirding.com/NYSbirdsSubscribeConfigurationLeave.htm > > ARCHIVES: > 1) http://www.mail-archive.com/nysbirds-l@cornell.edu/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: 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/nysbirds-l@cornell.edu/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/ --
