January 25, 2017:
This First Cycle-type gull with the characteristics of Slaty-backed Gull (Larus schistisagus) was at Elliot Landfill, Corpus Christi, Texas on February 13th, 2007.
Features that point towards SBGU:
1) structure: the legs are fairly wide-apart and shortish, and there is a bit of a droop behind the legs, plusa long neck. The short primary extension beyond the tail plus exposed secondary tips below the coverts create a dumpy, broad-winged effect.
2) legs strongly pink - more pink than nearby American HERGs (some HERGs can have strongly pink legs - but it is a typical feature of SBGU).
3) head with eye placed slightly forward of center, surrounded by a small dark patch and with a short dark line extending back from the eye; the crown and forecrown with obvious, cleanly-demarcated dark streaks.
4) dark tail lacks any barring - instead having pale specking scattered on the base of R6 and R5, plus variable "soft" pale tips to the Rs - one of the classic patterns for SBGU.
5) primaries and secondaries with clearly paler inner webs than outer webs (contrast less distinct on overall paler inner Ps); in flight the outer Ps (plus their coverts), secondaries and tail are similar in tone and darker than the rest of the upperside.
6) from above all non-worn greater, median, and larger lesser secondary coverts are very pale on large inner web, slightly darker on thin outer web plus with similar-toned subterminal mark across both webs - overall effect is of a very pale inner wing with rows of darker spots.
7) from above all primary coverts match their overlain primary in tone and pattern (i.e. paler inner web); alula feathers slightly darker - the darkest part of the upperwing.
8) On standing bird, visible outer Ps with pale, narrow, uniform-width fringing at tip.
9) dense dark markings on uppertail coverts and undertail coverts typical of all large North American gulls plus SBGU.
LINKS TO PHOTOS OF A SELECTION of SAME-AGE BIRDS FROM JAPAN:
note that the hot, sunny, sandy Gulf Coast beaches are different to the cool, cloudy, rocky coastlines that are the wintering grounds in Asia - bleaching and wear rates can be much faster in the Gulf of Mexico than in the eastern Pacific:
http://www23.tok2.com/home/jgull/DecSla/zDSCN1055.jpg - mid December
http://www23.tok2.com/home/jgull/080115/080115%20031_S.jpg - mid January
http://www23.tok2.com/home/jgull/SlaG1w01113/SlaG1w01113_3.JPG - mid January
http://www23.tok2.com/home/jgull/SlaG1w01113/Slaty1w.jpg - mid January; both are SBGUs - a nice demonstration of the variability in primary tone
http://www23.tok2.com/home/jgull/080115/080115%20122_S.jpg - mid-January; imagine this bird a month later and more sun-bleached and worn...
http://www23.tok2.com/home/jgull/080115/080115%20246_S.jpg - mid January
http://www23.tok2.com/home/jgull/040113/Sl_03.jpg - mid January; a darker individual but included to show what females can look like, structurally
http://www23.tok2.com/home/jgull/040113/Sl_08.jpg - Mid January; here's what the Ujihara's said about this bird: "A pale, advanced individual. This resembles somewhat Glaucous-winged Gulls. But its outer primaries and tail are dark in contrast to the rest. This type may suggest Glaucous-wingedXSlaty-backed as well, but I think this type is too common in Japan to be that, in comparison with the frequency of adults presumed to be the parentage. " - THEY DID NOT HAVE ANY MISGIVINGS ABOUT THE OTHER SBGUS LINKED ON THIS PAGE.
http://www23.tok2.com/home/jgull/070216/SLFL%20%2810%29.jpg - mid February
http://www23.tok2.com/home/jgull/070203/SBG%20%2810%29.jpg - early February
http://www23.tok2.com/home/jgull/070203/SBG%20%282%29.jpg - early February
http://www23.tok2.com/home/jgull/Sb1w_pCh.jpg - February
http://www23.tok2.com/home/jgull/Sb1s010427/Sb1s0104277.JPG - early April
http://www23.tok2.com/home/jgull/Sb1w010402/Sb1w010402_5.JPG - early April
http://www23.tok2.com/home/jgull/061101/Sb%20%287%29.jpg - November 1st; what would this look like in mid-February having wintered in the Gulf?
http://www23.tok2.com/home/jgull/061101/Sb%20%2812%29.jpg - November 1st; what would this look like in mid-February having wintered in the Gulf?
A page of birds from February 10th:
Two pages of birds from mid March:
A page of birds from early April:
A page from "eary Spring" - with primaries much paler than the TX bird:
http://www.birdskorea.org/Images/ID_Notes/Slaty-backed-Gull/image15fwslatynov22y2002gurya.jpg - a bird from Korea in November
http://www.birdskorea.org/Images/ID_Notes/Slaty-backed-Gull/image16bleachedfwslatymarch92003guryongpoa.jpg - a bird from Korea in March