Hi Tweets,

Responding to Ryan T Shaw, Michael Donahue writes:

>I would like to suggest that the bird you saw was a very worn
glaucous-winged gull. (Or even a worn western gull or GW x W hybrid.)
(snip why GW's get faded at the beach)

Roger that. This is also the time when faded Basic 1 Thayer's Gull Larus
thayeri can be mistaken for an Iceland Gull, L. glaucoides race kumlieni, by
appearing to be similarly pale.

>First and second winter glaucous gulls always have a bicolored bill. [BTW,
ageing them by plumage can be difficult due to the wide variation in
plumages of the two age classes, but second year birds generally have a pale
eye.]

The at-first-glance paradigmatic Basic 1 Glaucous Gull L. hyperboreus is a
very pale brown bird with white or very pale brownish outer primaries, dark
eye and bill in which the basal two-thirds to three-quarters is a bright
pink-flesh, distinctly tipped black, while the typical Basic 2 is white with
a very faint pale warm brown suffusion bestowing a peculiar pearly or
glowing quality unshared by other pale white gulls; on the Basic 2 birds,
the outer primaries are unmarked white, and the bill is again pale
pink-flesh for most of its length with the black tip taking about one-fifth
of the bill.

By the end of each wintering period, most of the birds in *both* age-groups
resemble the 'all-white' second-year plumage, with some birds gaining a
pale--but not the full citrine-yellow--eye of the adult. By this time, also,
some of the Basic 2 birds will show a pale tip to the bill, confining the
black to a band not too unlike that of adult Ring-billed Gull L.
delawarensis--this pattern becomes much more obvious on Third-year Glaucous.

The quickest way to separate them from equally-pale Glaucous-winged Gulls L.
glaucescens is to note the bill colors and patterns: in similar 'all-white'
plumage (usually worn Basic 1), Glaucous-winged Gulls show an all-black
bill. Some faded late-Basic 2 GW's look like an 'all-white' bird with a
partially-emergent adult bill; that is, pale-based and black-tipped. So, how
to separate from late-winter Glaucous? Note the bill-pattern: on a Glaucous,
it's almost always a very clean vertical division between the pale and black
areas whereas the Glaucous-winged shows a messier, less-distinct cut-off
with the black often curving well back along the cutting-edge (tomus), and
the pale basal areas tend to be yellowish rather than flesh.

Some Basic 1 Glaucous that I've seen have been *very* dark, though, as dark
as a typical Basic 1 Glaucous-winged, and such a bird could easily be
overlooked in a winter flock containing Basic Glaucous-winged. No GW of that
age, though, would have the combination of unpatterned pale grey-brown to
brownish-white outer primaries and conspicuously black-tipped pale bill.

A third, outside possibility for such a bird as Ryan saw is a faded
late-winter Basic 1 Slaty-backed Gull L. schistisagus: from the photographs
of this age-group of that species increasingly to be found around the Web,
it's often essentially an overall white or very pale bird--the blackish-grey
back doesn't begin to emerge until its second year--with a characteristic
set of dark markings and patterns on tail and flight-feathers, just like
some of the faded hybrids between Western Gull L. occidentalis and
glaucescens. The fun begins with some of these strange birds which don't
seem to fit the usual patterns of that hybrid-type. The ID possibilities
start getting kind of hairy here, as others to consider, if only to
eliminate them--are, besides the Slaty-backed, Vega Gull L. vegae,
schistisagus X glaucescens hybrids from the Asian contact zone, and another
really out of left field, Siberian Gull L. taimyrensis (CA birders think
they've got one--a biggish, dark-mantled gull with long, bright yellow legs).

Ah, gull ID: don't think of it so much as losing your mind as gaining an
obsession.

Michael Price
Vancouver BC Canada
mprice at mindlink.net