An assortment of white-winged to brown-winged gulls from Gloucester, MA
17 February 2008
The following images were taken during a day of gull-watching (with Rick Heil, Ian Davies, and Luke Seitz) in Gloucester, MA, and illustrate the range of variation in the Iceland Gull (Larus glaucoides/thayeri) complex. The thousands of large gulls wintering in this area have provided an exceptional opportunity (for those with the stomach!) to study this confusing complex.
Just what is attracting all these gulls seems to be a mystery, but there must be a lot of it! The high percentage of first-year birds, among all species, is quite striking and curious.
All images were taken with a Canon 20D camera and 100-400 Canon IS lens.
The spectrum:
The three gulls in the foreground, all in first-winter (or first-cycle) plumage, are members of this confusing complex, and illustrate the west (dark) to east (pale) cline. The left-hand bird seems to fit what is currently considered (by most anyway) to be a separate species, Thayer's Gull, though perhaps at the pale end of the spectrum for that form. The middle bird is strikingly white and appears to be a good candidate for the nominate (eastern) form Iceland Gull (though only its DNA knows for sure!). The right-hand bird is a fairly typical - if there is such a thing as "typical" - "Kumlien's" Gull, which is either a hybrid between the western and eastern forms, or perhaps just represents the middle portion of the east/west cline.
Larger images of the first two birds, as well as some other "Kumlien's" types, are below (click on the thumbnails).
Additional photos of the apparent "Thayer's" Gull; The
first two images provide a good comparison with a similarly plumaged Herring
Gull in the background:
These two images are of the extremely pale individual that may be the
nominate race of Iceland Gull; whatever it's DNA, it's a lovely bird!
Three different first-winter "Kumlien's" Gulls; the
third individual (last two images) has 2-3 damaged primaries on its left wing:
A lovely second-winter "Kumlien's" Gull - a plumage
not seen often in this area; the primaries on this individual are at the dark
end of the spectrum for this form:
