Very fascinating discussion and a welcome respite from the usual reports. The "Iceland Gull" complex on the taxonomy of Thayer's, Kumlien’s and Iceland Gull is a much discussed topic that I don't see ending any time soon.
The argument for hybridization between Iceland (glaucoides) and Thayer's have been made in the past but as of yet *(as far as I have read)* no "acceptable" research has proven this to be true, which supports the argument made by Shai. R.R. Snell refuted the work presented by N.G. Smith on hybridization of Iceland and Thayer's and I don't believe Snell's work has ever been disputed*. *To muddy things a bit more, we *(most of us)*assume that Thayer's is a full species of its own. What if it is not and is just a subspecies of Iceland Gull? As Julian pointed out, there appears to be more confusion based on myths rather than on quantitative and qualitative scientific study, on what really accounts for the paler primary candidates of Iceland Gull vs the darker primary types. Until any concrete evidence is provided that there is a "difference", it is probably just safe to refer to them all as just "Iceland Gulls". Out of curiosity, was there any vocalization studies ever done on paler primary Iceland Gulls vs the darker primary types? It would be interesting to know if the calls leaned one way or another *(nominate Iceland or Thayer's)* based on primary pigmentation. I not sure if it will prove anything but it would be interesting to know. Going back to what started this discussion, Steve's Gull from the 12th, could very well be the same individual I and others saw and photographed back in January 2013 at the same Jones Beach West End II location *(Shai's photo on Steve's website goes back as far as 2006).* The dark primaries on the January 2013 bird also caused some debate for a possible Thayer's but in the end it was ruled a Kumlien's type Iceland. Photos from that bird are online here - http://birdingdude.blogspot.com/2013/01/new-years-day-long-island-and-bronx.html Very enjoyable discussion which encouraged me to do more reading up on the topic, so thank you Steve, Shai, Mike, Phil and Julian. We need more teaching moments like these on the list serves. Cheers! Andrew Shaibal Mitra via<http://support.google.com/mail/bin/answer.py?hl=en&answer=1311182&ctx=mail> list.cornell.edu 9:35 AM (6 hours ago) to nysbirds-l Given that this conversation found me four times independently in one day, I think it's worth at least collecting some of the threads, if not measuring them or tying them together! My perception is that the Iceland Gulls I see on Long Island and in coastal southern New England are very variable in terms of pigmentation (e.g., wingtip pattern and intensity and iris color) but not in other ways (e.g., size, structure, seasonality, habitat preference, and feeding habits). Even mantle color is close to uniform, ranging from just barely paler than American Herring Gull and Ring-bill to noticeably paler than these reference species. When I say that they are relatively uniform and distinctive in terms of size, structure, seasonality, habitat preference, and feeding habits, it's important to calibrate this within the range of options occupied by large white-headed gulls as a group, all of which are incredibly similar overall and broadly overlapping in all the ecological variables. Thus, I'm not saying that Iceland Gulls never eat garbage like Glaucous Gulls, never eat ducks like Great Black-backed Gulls, never sit in parking lots like Herring Gulls, never dabble plankton like Ring-billed Gulls, or never hunt pelagic fish like Lesser Black-backed Gulls. Most of these species do most of these things from time to time, but each has its own distinctive niche around here, and my perception is that Iceland Gull's niche is just as distinctive as that of any of the other regular species. When I say that large white-headed gulls are incredibly similar in overall size and structure, I mean to point out that the variation within species is very large relative to that among species. One way of illustrating this is to consider that basically all the possible combinations of basic size, mantle color, leg color, and eye color are occupied by at least one species, and that people have had a hard time deciding what to do when populations from different parts of the world show similar combinations: Kelp Gull was for a long time considered a subspecies of Lesser Black-backed Gull (!), Armenian Gull is perversely similar to California Gull, etc. Perhaps the most extreme and vexing example of this phenomenon involves American Herring Gull and European Herring Gull, which, although basically identical as adults, are apparently not closely related. In view of all this, our Iceland Gulls seem very distinctive and stable to me, in every way but one (or two): wingtip pigmentation (and maybe iris pigmentation). The reason that I don't call these birds "Kumlien's Gulls" is that to do so would be to imply that we regularly see or expect to see any non-kumlieni Iceland Gulls. I do not believe that nominate Iceland Gulls occur here regularly (an odd vagrant from time to time is possible but would not be identifiable), nor do I think that, among our Iceland Gulls, those with paler wingtips are more closely related to nominate birds, or that those with darker wingtips owe this to Thayer's or Herring or other ancestry. As described above, it is always possible that we could be tricked from time to time by some completely different species or hybrid combination that happens to line up with a similar character combination, but this should sort out under the weight of long-term evidence. Because we have a series of carefully written books, we know not only that this variability in wingtip pigmentation has been around for more than a hundred years, but also that the pigmentation distribution has changed rather markedly over that time. Writing in 1923, Griscom clearly implies that the Iceland Gulls that he perceived as regular on Long Island had white wingtips. This is because he explicitly cites one specimen and one sight record of Kumlien's Gull, proving that observers were aware of and looking for the possibility of wingtip pigmentation. By 1964, Bull described a very complex situation which defied simple summary, but in which it is clear that Iceland Gull was perceived to have increased in overall frequency, and that both "white-winged" and "gray-winged" individuals were well represented. Nowadays, it is clear to me that the white-winged end of the distribution is much scarcer than it was previously (although it is still encountered fairly regularly). Thus, wingtip pigmentation in North American Iceland Gulls is and has been variable, and it has shifted toward the darker end over a century of observation. And why shouldn't it have done so?--characters evolve all the time. The notion that this shift has been a consequence of hybridization between white-winged, glaucoides-like birds and Thayer's Gulls, although widely accepted among birders, seems like special pleading to me, and much less plausible than the simple alternative of character evolution within a variable population. This is because the frequency of a trait of hybrid origin is not expected to exceed the rate of hybridization, relative to the overall population sizes. Thus, the hybridization hypothesis would require not only that hybridzation occurs regularly, but that it occurs at extraordinarily high rates relative to the overall population sizes. Needless to say, detailed, quantitative evidence of this kind simply does not exist. Also, if the hybridization hypothesis were true, why have our Iceland Gulls remained so consistent and distinctive in size, structure, and ecology—indeed, in every respect other than pigmentation—rather than evincing Thayer’s influence in these other respects? It is true that we also lack direct evidence that natural selection has been pushing pigmentation along, but this seems much more parsimonious to me, based on current evidence. Shai Mitra On Thu, Jan 16, 2014 at 3:37 PM, julian hough <[email protected]> wrote: > Phil's point is true and I don't believe I was a proponent of stating that > I didn't think hybridization was a likely cause. I am just not well-read or > informed at all about what really is going on with the whole > Iceland-Thayer's relationship..it is a murky gene pool with no lifeguard. > > Julian Hough > New Haven, CT 06519 > www.naturescapeimages.wordpress.com > > ------------------------------ > *From:* Phil Jeffrey <[email protected]> > *To:* julian hough <[email protected]> > *Cc:* & [NYSBIRDS] <[email protected]> > *Sent:* Thursday, January 16, 2014 3:30 PM > *Subject:* Re: [nysbirds-l] Iceland gulls > > To me it makes no more sense to dismiss hybridization amongst those two > species as a mechanism for primary darkening than it does to invoke it. > Just because it's not proven doesn't mean the alternative is true either. > It would be one thing if, say, glaucoides in Iceland (the country) were > darkening its primaries or Glaucous Gulls or even (American) Herring Gulls > were seen to do so, but I'm not aware of any such trend. A Western birder > might find the idea that two similar gull species *not* hybridizing to be > alien to their experience, for example. > > From my POV it makes sense to attempt to normalize intra-(sub)species > variation by looking at that spread in Iceland glaucoides populations in, > say, Iceland itself. While more or less anything can happen with gulls, > I'd be a lot less likely to find the "intrinsic variation" idea worthy of > Occam's Razor if the range of variation in the > bird-oft-referred-to-as-Kumlein's substantially exceeds that in the > glaucoides subspecies. > > Or, more plainly put - point me to the preponderance of evidence that > hybridization is *not* going on in this form of Iceland Gull (or whatever > it is). > > Phil > > > > > On Thu, Jan 16, 2014 at 12:29 PM, julian hough <[email protected]> wrote: > > Shai distilled down some common-sensical aspect of the complications > surrounding Iceland Gulls and what our perceptions are about how solid > these are as a taxon. As an exiled Brit, I grew up on nominate > glaucoidesIceland Gull and it often involved searching through these for a > vagrant > kumlieni "Kumlien's" Iceland Gull. > It is more a continuing bad-habit that I refer to them as Kumlien's Gull > here since, as Shai points out, there really isn't that much of a need for > separating them to sub-species level in the US, as perhaps there is in > Europe where kumlieni shows up more regularly. > > Interestingly, adult iceland Gulls were scarce here in New England > compared to the numbers of first-cycle birds so it was always cool to see > an adult. The ones I have seen here in CT have all been mid-grey – to pale > grey pigmented and black-primaried individuals seem rather uncommon at this > latitude. Not sure that as quantitative evidence it amounts to anything > from a scientific aspect but I wonder what drives the range of pigmentation > in these birds…hormones, geography, actual hybridization? > > There seems to be a lot of talk – confusion – is perhaps more apt about > what these birds are based on perpetuated myths about "hybrid swarms "of > kumlieni or interbreeding populations of kumlieni x thayeri etc and as > Shai points out it may not benefit us, in lieu of quantitative and > qualitative scientific study, to continue thinking that black-primaries > Iceland Gulls here in the US have "x" amounts of thayeri genes flowing > through them and more whiter-primaried birds have perhaps a more > glaucoides influence. > > As for separating adults from nominate glaucoides Iceland Gulls from > Northern Europe, certain birds in Newfoundland seem to check the right > boxes so with care the odd bird might be identifiable by sharp observers. > > Intrestingly, the long-calls of these white-winged gulls was recently > studied and written up by Belgium birder Peter Adriaens here: > > http://birdingfrontiers.com/2014/01/09/calls-of-thayers-kumliens-and-iceland-gulls/ > > Good birding, > > Julian > > Julian Hough > New Haven, CT 06519 > www.naturescapeimages.wordpress.com > > > -- > *NYSbirds-L List Info:* > Welcome and Basics <http://www.northeastbirding.com/NYSbirdsWELCOME> > Rules and Information <http://www.northeastbirding.com/NYSbirdsRULES> > 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> > BirdingOnThe.Net <http://birdingonthe.net/mailinglists/NYSB.html> > *Please submit your observations to **eBird*<http://ebird.org/content/ebird/> > *!* > -- > > > > > -- > "If you lie to the compiler, it will get its revenge" > - Henry Spencer > > > -- > *NYSbirds-L List Info:* > Welcome and Basics <http://www.northeastbirding.com/NYSbirdsWELCOME> > Rules and Information <http://www.northeastbirding.com/NYSbirdsRULES> > 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> > BirdingOnThe.Net <http://birdingonthe.net/mailinglists/NYSB.html> > *Please submit your observations to **eBird*<http://ebird.org/content/ebird/> > *!* > -- > -- NYSbirds-L List Info: http://www.NortheastBirding.com/NYSbirdsWELCOME http://www.NortheastBirding.com/NYSbirdsRULES 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://birdingonthe.net/mailinglists/NYSB.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
