back to the Gull ID MainPage
Iceland x Thayer's
|Fig 1) This could be a pure Thayer's, but compare the darkness of the outer primaries with a more obvious second winter Thayer's Gull . On this bird, the primaries are the same shade of brown as the markings on the wing coverts. February 24, 1998. San Francisco Bay Area, California. Photos courtesy of Mike Rogers.|
Figs 2 and 3) These forms are often retarded in their molt, showing limited adult gray
in the mantle in their second cycle. However, the marbled coverts and tertials indicate a
second cycle bird. Note the size and structure difference with the adjacent Herring Gull.
Also note how the darkness/lightness of the bird varies across the two photos.
January 22, 2012. Saginaw River, Michigan. Photo courtesy of Dan Duso.
Fig 4) This appears as a petite, pale second winter Thayer's.
The obvious strikes against pure Iceland are the dark tertials on a pale
bird, the dark secondary bar (barely visible on the distant wing), the solid areas to the
tail, and the dark primaries. Structurally, it's more toward the Iceland end of the spectrum.
The contrasting dark tertials are evident.
appearances of this photo, the bird was nearly the same size as adjacent California Gulls,
though with a more rounded dove-like head and shorter, slimmer bill, and was also slightly
smaller than an adjacent Thayer's Gull.
February 10, 2000. Davis, California. Photo courtesy of Bruce Webb.
Fig 5) While most second cycle Thayer's have worn white coverts by March, this bird has nearly
March 1, 2012. Davis, California. Photo courtesy of Steve Hampton.