Great Black-backed Gull

Great Black-backed Gull (marinus)

IMAGES:

First Cycle
Second Cycle
Adult

DESCRIPTION:

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
	FIRST CYCLE	SECOND CYCLE	THIRD CYCLE	ADULT
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
PRIMARIES (folded):	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
PRIMARIES (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
SECONDARIES (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