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Thayer's Gull

Note: "Kumlien's Gull" is considered here to be Iceland x Thayer's hybrid and is in the hybrid section. See this page for a note on taxonomy and a proposed Thayer's/Kumlien's/Iceland scoring system.


First Cycle
Second Cycle
Third Cycle


THAYER'S GULL (22-25"; 50-55") thayeri

BILL SHAPE: short, thin, and straight; about 3-4x eye diameter; little gon angle; curve of culmen is gentle
HEAD SHAPE: smooth and often very rounded, somewhat dainty or dove-like; sometimes w/ sloped forehead
WING EXTENSTION: slightly longer than bill length
POSTURE/HABITS: slightly heftier than Iceland, smaller than Herring
BILL COLOR: solid black; some w/ flesh base to lower mandible pale flesh w/ variable dark tip; some may be mostly dark variable flesh to yellow w/ dark tip or subterm band; may show some gon spot pale yellow, may have greenish tone w/ brighter tip; gon spot red to orange-red, small and flat, not extending to cutting edge; rarely w/ dark mark
LEG COLOR: dark pink dark pink dark pink dark rose pink
IRIS/ORB RING: dark usually dark usually as adult iris usually dark; may be honey or even yellow; orb ring
HEAD: covered w/ thin diffuse g-b streaks; aurs often solid; pale on aur edge, upper nape, near bill and on throat white w/ fine light streaking on crown and aurs; heavy blotching often around nape to breast sides as adult but w/ more extensive streaking over head, neck, and upper breast light streaks on crown and aurs, paler and browner than on smithson; extensive thick blurred streaks on lower nape to breast sides
UNDERPARTS: breast fairly uniform pale g-b, diffusely streaked or splotched; belly uniform and slightly darker; undt covs barred variably smudged, especially on belly; undt covs lightly barred white; some splotching from breast may extend to belly white
dark g-b w/ pale crescents of feather tips, sometimes worn off by late winter variable gray w/ pale crescents as adult, but w/ smaller A-spots A-spots evenly sized or slightly decreasing; A7 slightly larger than eye; A10 same size or slightly smaller than eye
(in flight):
outer webs of outer Ps dark, inner webs light, producing a striped effect; pale window on inner Ps; silvery pale from below w/ thin dark trailing edge to outer Ps as juvenile but w/ pale webs nearly white; inner Ps nearly white; thin dark trailing edge to outer Ps from below, otherwise quite white ... limited black on Ps; huge terminal mirror on P10; large mirror on P9; black confined to outer webs and subterm bands on P5-9; large white tongues on P6-8; pattern much fainter from below, showing dark gray subterm bands only; gray undersides show little contrast
(in flight):
like Ps, outer webs dark and inner webs light, but w/ pale fringe; silvery pale from below washed g-b outerwebs and pale inner webs w/ pale fringe; whitish from below ... adult gray w/ white trailing edge about ½ bill length
TERTIALS: usually a little darker than covs, lighter than Ps; solid g-b w/ variable pale subterm marks and pale tip; some w/ pale notches along sides med g-b w/ extensive white marbled tips and fringes adult gray; may have trace of g-b adult gray w/ white crescent about 3/4 bill length
GREATER COVERTS: completely barred or spotted g-b and white, appearing checkered white w/ irreg fine brown barring or marbling adult gray; may have trace of g-b adult gray
LESSER & MED COVERTS: like scaps, but w/ smaller anchors, appearing neatly checkered white w/ irreg fine brown barring or marbling adult gray; may have trace of g-b adult gray
SCAPULARS: pale w/ large g-b subterm anchors, giving a checkered look; anchors may be larger and more solid, giving a scaled look usually mixed w/ adult gray; some w/o adult gray, appearing like a muddied version of 1W adult gray adult gray w/ white crescent about 1/3 bill length
BACK: dark anchors larger, making most of feather dark, giving scaled look adult gray mixed w/ g-b; some w/ little adult gray, looking pale and muddy adult gray adult gray is med light; darker than smithson, lighter than California
RUMP: heavily barred paler; lighter barring white white
TAIL: large broad dark band, contrasting w/ upperparts, w/ pale fringe, barred outermost webs and barred bases to outer few retrices gray tail band still darker than rest of back; bases of retrices whitish white w/ irreg broken subterm band white

The was table created by Steve Hampton and is intended to futher our knowledge of gull identification. Please email me at if you have any suggestions for updating or improving this table. Thanks.