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Great Black-backed Gull (marinus)


First Cycle
Second Cycle


GREAT BLACK-BACKED GULL (28-31";60-66") marinus

BILL SHAPE: very large and deep; 5-6x eye diameter; gon angle moderate; culmen straight w/ steep vertical hawk-like tip
HEAD SHAPE: large w/ long flattish crown, so that eye appears tiny; heavy brow
WING EXTENSION: 3/4 - 1x bill length
POSTURE/HABITS: obviously larger than Herring w/ heavier, more lumbering flight
BILL COLOR: black, sometimes w/ slight pale base; often w/ tiny white tip variable; usually pale at base; dark subterm band or larger dark area; pale tip whitish to yellowish-pink w/ variable dark subterm marks; often hint of gon spot pale yellow w/ orange or red gon spot
LEG COLOR: dull pink dull pink usually as adult pale grayish-pink or flesh
IRIS/ORB RING: dark dark or pale as adult pale yellow, but often dark from a distance; orb ring red
HEAD: quite white w/ some streaking on rear crown, rear aurs, nape, and neck sides; dark crescent from front of eye, under eye, to short postocular line white w/ faint streaking around eye and rear aurs; streaking on nape and neck sides; dark eye crescent as adult mostly white; dark eye crescent and thin dark streaks on rear aurs and nape visible at close range
UNDERPARTS: breast white or lightly speckled; belly and flanks boldly blotched white w/ mottling from breast sides down flanks largely white; may have faint marks white
blackish; pale crescents at tips in fresh plumage blackish; pale crescents at tips in fresh plumage as adult but A-spots may be smaller all A-spots larger than eye
(in flight):
dark w/ moderate pale window on inner Ps, more notable from below dark w/ moderate pale window and dark subterm marks on inner Ps; trace of mirror on P10 possible as adult but more black and smaller mirrors, often not terminal; black often to P5 large terminal mirror on P10; large mirror on P9 (rarely terminal); rarely small mirror on P8; black band on P6; slender white tongue on P6, sometimes to P7 or even P8; very dark contrast from below
(in flight):
dark w/ pale fringe blackish w/ broad pale fringe as adult adult gray w/ broad white trailing edge, about 1/2 bill length; often show pale bases from above when worn
TERTIALS: dark g-b w/ large white tip, edges, and single large notch on sides dark g-b w/ extensive marbled and white tips mixed adult gray and brown w/ large white tip adult gray w/ large white crescent, about 1/2 bill length
GREATER COVERTS: white w/ rows of dark g-b spots; outer webs more solid dark on outer feathers entierly marbled dark g-b and white, w/ obvious white subterm spot or bar mixed adult gray and brown, especially inner feathers adult gray
LESSER & MED COVERTS: pale w/ large dark g-b subterm anchor, appearing checkered pale w/ dark subterm anchor, appearing checkered or barred adult gray w/ brownish tone adult gray
SCAPULARS: as L&M covs as L&M covs; may show little or no adult gray adult gray; may have brownish fringes adult gray w/ small white crescent; about 1/3 bill length
BACK: as L&M covs, but narrower edges creates darker look as scapulars; adult gray by summer as scapulars adult gray is very dark, nearly black
RUMP: white w/ faint scattered streaks; dark arrowheads around tail base largely white white white
TAIL: white base w/ irreg. jagged black subterm band w/ thin wavy inner band and other spots; outermost webs white white w/ large variable mottled subterm band; outermost webs white white w/ variable broken subterm band or marks; outermost retrices white 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.