"Thayer's Gull" - Categorized Inaccurately For Decades

I guess I’ll cut to the chase- I’m a veteran student of Larus (at it 40+ years!) that knows his stuff. Of course, many would claim this, but remain sadly ignorant to the true nature of this family. A distressing percentile of so-called “gullers” are obstinate in dismissing my findings, whether out of convenience or the belief that they have this clade “all figured out”, I am not not sure. But it is not wise to ignore 40+ years of experience and research! Through many decades of astute observation, I have concluded that there is a previously unrecognized western continuum of North America’s Herring Gull (now sadly called “American Herring Gull” by certain “authorities”!), averaging smaller, shorter-billed, dark-eyed, and with slightly paler primaries incorporating a variable amount of black markings. Most gullers are no doubt familiar with the purported “Thayer’s Gull”, considered by various bodies to be either a distinct entity or a part of the ever-expanding “Iceland Gull complex”. The truth (long suspected by the late Jim Pranty) is that it is neither, but fits the aforedescribed western cline of Herring Gull rather nicely. If I may be blunt, this seems so obvious a conclusion that it is greatly to my surprise that the oft-revered minds of this community have not already come across this. The majority of gull-watchers no doubt possess a basic idea of the appearance and alleged distribution of “Thayer’s” and “American Herring ” gulls. In the following paragraphs I will refer to them as though they are distinct forms for the benefit of those not already familiar with my findings. Without further ado, here is the overwhelming evidence in support of this truth: -“American Herring Gull”, by the widely accepted (but incorrect) definition, nests northwards in the east to Baffin and Southampton Islands in the Canadian arctic. I might add that it does so allopatrically with the “Kumlien’s Iceland Gull”. Curiously, it is not present as a nesting entity on islands at similar latitudes in the western Northern American arctic. Instead, it is replaced by the “Thayer’s Gull”! This discontinuity is not coincidental, however. It reflects an overlooked ecological and evolutionary reality: this “Thayer’s Gull” is simply a western morphological expression of the “American Herring Gull”. -The observed differences are predictable phenotypic responses to environmental gradients and genetic isolation. Consider primary pattern, often overemphasized in the delineation of Larids. “Thayer’s Gulls” (henceforth referred to as TG since I can no longer bring myself to write out the name and lend it a shred of credibility!) often exhibit restricted black in the primaries compared to “American Herring Gulls” (AHG). This pattern mirrors similar clines in other widespread species, such as the “European Herring Gull” and the Lesser Black-backed Gull. In these cases geographic variation obviously does not warrant species-level distinctions. Of course, the same is true of other traits often cited as causes for TG to be recognized as a distinct taxa, such as bill length, size, mantle shade, leg colour, and various structural cues. The well-documented variation present within TG is further evidence of it being a cline, with longer-billed, darker-tipped birds representing the easternmost portion of the “TG range”. Meanwhile, the occurrence of dark-eyed birds that seem to otherwise fit the bill for AHG remains entirely unexplained. I would call any of these individuals “eastern TG” without a second thought. -Having studied Larus in British Columbia, Washington, California, the Midwest, and the Great Lakes, I would not be surprised if I have observed more TG-types than any gull-watcher alive. Though hearing this may put some weathered gull-watchers in a state of distress, TG and AHG are often entirely indistinguishable. Many times I have encountered individuals blending traits of these purported distinct forms! AHG-types with what many would consider typical TG primary patterns, TG-types with long bills and pale irises, and everywhere in between. Of course, juvenal and first alternate plumages remain entirely unidentifiable. So, it is clear that TG is not worthy of recognition in any form other than as a regional expression of the Herring Gull. In my view, it is reckless taxonomy to continue to jump through hoops to call this entity anything but what it is! This obsession with compartmentalizing gulls into strict categories has blinded those who call themselves gullers to their fluid and variable nature. To further illustrate my findings, I have included photographs of 3 individuals representing the sections of North America's impressive Herring Gull cline. All pictures are taken from the Ebird web site, which, if nothing else, functions as a database of individuals photographed by the gull-watchers that carry cameras.

Figure 1: a typical eastern or taiga Herring Gull, presumed to be nesting in North America's boreal forest, the Great Lakes region, or the Atlantic Coast. Photo by G & B, Ebird web site.

Figure 2: a typical western arctic (northwestern) Herring Gull, likely nesting on islands in Canada's Nunavut or Northwest Territories. Note that, aside from the dark eye, it is nearly identical to a typical eastern/taiga Herring Gull. Photo by Brian Sullivan, Ebird web site.

Figure 3: an eastern/taiga-type Herring Gull, typical except for the dark eye. This individual almost certainly originates from the easternmost colonies of so-called "Thayer's Gulls". Photo by Cesar Ponce, Ebird web site.

I will update this page as my findings develop.

Gene.