Update: August 4, 2000:- Thanks to
recent postings to ID-Frontiers, I found this wonderful site with
lots
of Gulls in Japan. There are lots of 1B Slaty-Backs to compare
to this bird, but I especially draw your attention to the
first image on this page of SBGUs - the tail pattern is an
EXACT match for the La Marque, Texas bird (even down to the pale
tips on the central retrices), and the far wing shows how the
primaries look when held in a more-pointed manner - and are similar
to the Texas bird; I contacted the photographers (Osao Ujihara
and Michiaki Ujihara) and they tell me that this photo is from
Chosi, Chiba in mid-winter, and "tail-patterns like this
bird are not rare, but the majority of slaty-backed gulls have
less white in their tails, and a minority of them have all-dark
tails like western gulls." The Texas bird would be
a fair representation of such an individual that went on to spend
a few months on the sunny, sandy Texas coast, no? - any
comments would be appreciated - thanks.
Update: April 9, 2000:- I just received
some photos from Tony Leukering of birds in westernmost Alaska,
click here and here
to see them; like those by Peter Post they depict first-summer
SBGUs as having a darker row of scaps just above the lesser wing-coverts
- see bottom of this page for a new scan of the
Texas bird, pointing to three similar such darker scaps ("A"),
plus a video grab by John and Barbara Ribble that shows a little
more of the underwing.
Update: April 8, 2000:- I located
some images of first-summer SBGUs at Robert Lewis' gull site;
if you click
here and look at image C (the smallish white imm. looking
at the camera is quite similar to the Texas bird in build, plumage
and bill pattern); image D (the four 1st-alternates in this photo
all show some darker lateral scaps just above the lesser coverts),
and image E (again the lateral scaps are darkest, and note the
tail pattern). These photos from Siberia were taken in mid-June;
keep in mind that the normal range of SBGU is much more humid
and less strongly sunny than the Texas coast, thus an early April
bird in Texas may easily match the degree of wear/fading normally
seen on summer birds in their normal range.
This gull was photographed at La Marque Racetrack, near Galveston,
Texas on the 3rd of April, 2000 by Martin Reid. The somewhat darkish
eyes (just a hint of paling), worn, juvenile-looking primaries
and mottled uppertail coverts ( see below) point to it being a
bird molting into first- alternate plumage - yet in some ways
(body and bill color, apparent color/pattern of retained worn
scaps) it looks more like a 2B - 2A bird:
It was the size of a smallish HEGU:
and the newer lower scapulars ( only a few on each side) were
clearly those of a dark-backed gull:
-but there is a clear pale window on the inner primaries that
would be hard to explain by wear/fading alone; also look at the
very dark underwing coverts next to pale flight feathers and fairly
clean whitish flanks; and look at the the outer primaries: thin
pale lines within the dark brown indicate pale innerwebs to at
least P8, plus the outer five end in bare shafts that indicate
paler tips have been worn-off:
- and that tail pattern: in the field while standing, the basal
"band" was clearly paler BUT was not white - instead
it was pale brownish; the dark subterminal band looked even when
perched but had some irregular lengthwise protrusions into the
paler basal area when spread; also note that the poor view of
the under-primaries appears to show them as quite pale:
The legs were vividly rose-pink, and the secondaries were paler
on the inner web such that in real life and in the flight photos
there was the "venetian-blind" effect that is associated
with Thayers and Slaty-backed:
I found this shot below (taken to document the presumed 1B/2B
HEGU with a yellow-tipped pink bill to the right); this was the
moment in the field when I first noticed this worn, darker-mantled
bird with a whitish head:
- and a close-up shows how the tail looked when folded: mostly
dark but with a pale brownish basal "band" (starting
where arrow is pointing); also note the slightly paler central
pair of rectices that are also visible in the flight shots:
The only species I can think of that fits would be a worn, female
(size, head/bill structure) Slaty-backed Gull. I refer you to
the segment on Dunn's LARGE GULLS video: in the introduction piece
for Slaty-backed Gull at ca.1:42:35 - it shows a small female
third-basic SBGU (with GLGUs and an adult Vega Gull) that in size
and structure - not plumage - resembles this bird; then at 1:52:21
(a still shot of a flying 1A SBGU after a flight sequence) the
commentary is saying how the tail looks "almost entirely
dark", yet it shows a paler (but not white) narrow basal
band; then at 1:53:28 there is a still of a juv SBGU with spread
uppertail, showing extensive pale at the bases of the outer retrices;
finally, look at Grant's GULLS book, photo 500 (page 336), as
it depicts a 1A that shows a similar tail/rump pattern to the
La Marque bird. I would appreciate receiving
comments.
