Tuesday, February 5, 2013
Herring Gull: that name covers a lot of stuff
It takes a Herring Gull about four years to achieve its adult plumage, and every age class floats in the scene above. The dark brown birds are first and second-cycle gulls; they'll become cleaner, neater, and grayer and whiter with age.
HERE, and HERE - the bird in the center left of the photo grabbed everyone's eye. For one, it is already in its breeding finery, with gleaming white head and neck, none of the dirty brown mottling that winter-plumaged Herring Gulls should still be retaining.
There was much debate about its identity, and we'll come back to that momentarily.
Lesser Black-backed Gull is essentially part of the Herring Gull complex, and this closely allied species regularly hybridizes with Herring Gulls. Ohio did not record its first Lesser Black-backed until 1977, but the numbers of this European species have skyrocketed since. Along with them have come more records of apparent hybrids.
At the time, in the field, we felt that it must be a hybrid, possibly between Lesser Black-backed and Herring. Later, I saw a note posted to the Ohio Birds Listserv by John Pogacnik, who was there later and saw the bird. John put forth the theory that it might be a Vega Gull, which is a largely Asian subspecies of the Herring Gull, and is treated as its own species elsewhere in the world.
Find an expert. A major shortcoming for us who spend most of our time in the midwestern U.S. is that we just don't see or gain familiarity with Vega Gull. John pointed me to an excellent article detailing the Vega Gull, HERE, by Chris Gibbins. Dr. Gibbins spent time looking at scores of Vega Gulls in Japan, where they are common, and exhaustively documented and described what he saw.
I sent Chris a series of images of our mystery bird, and received a reply in short order. In a nutshell, he did not think it to be Vega, due to the darker mantle, pale eye, and wing pattern. He also noted that, if it were a Vega, it should still have a dirty brown head and neck as the bird still should be in winter plumage. Perhaps most importantly, his overall initial impression was not of a Vega Gull, and that means something coming from someone who has taken the time and effort to carefully study the species in the field.
Sometimes, and this is very dissatisfying to some of us birders, a label just cannot confidently be placed on certain birds. But perhaps you know what this Mystery Gull is. If so, please do tell.
When stumped by oddball Herring Gulls and their ilk, I can take solace in this quote from Steve Howell's Gulls of the Americas: "The Herring Gull complex... constitutes one of the most problematic issues in contemporary avian taxonomy". Couple that statement with the large white-headed gulls' penchant for mating with other species, and we sometimes end up with weirdo birds that'll drive you up the wall.
I promise to steer clear of gulls for a while.
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