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/ --
