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Lesser Black-backed Gull
(graellsii/intermedius)


IMAGES:

Second Cycle
Adult


DESCRIPTION:

LESSER BLACK-BACKED GULL(20-24"; 49-50") graellsii/intermedius

BILL SHAPE: slightly smaller and thinner than Herring; 4x eye diam.; gon angle small to medium; culmen slopes gently to tip
HEAD SHAPE: rather rounded with slightly flat crown
WING EXTENSTION: long; 1-1.5x bill length
POSTURE/HABITS: usually appears smaller and more graceful than Herring
FIRST CYCLE SECOND CYCLE THIRD CYCLE ADULT
BILL COLOR: black; no pale base until summer variable; usually pale w/ black subterm area yellow w/ dark subterm band or mark dark yellow w/ red or orange-red gon spot; pale tip
LEG COLOR: dull pink usually pink to pale pink yellowish to grayish-flesh pale to dark yellow
IRIS/ORB RING: dark dark or pale as adult pale yellow; orb ring red
HEAD: rather pale, w/ dark mottling or streaking around eye, auriculars, and rear crown; young birds have solid blackish patch from front of eye to auriculars white w/ thin streaks over crown and aurs; darker streaks on nape and neck sides as adult extensively streaked w/ fine lines over crown and face; thicker streaks on nape and neck sides to upper breast
UNDERPARTS: blackish mottling from lower nape and neck sides to breast sides and flanks; belly paler; undt covs spotted white w/ extensive dark streaking or mottling on breast sides and flanks white white
PRIMARIES
(folded):
blackish blackish black; A-spots tiny or lacking A-spots evenly spaced except 9-10 closer; all are smaller than eye
PRIMARIES
(in flight):
blackish above and below blackish above and below as adult but A-spots and mirrors often lacking; black area slightly larger med to large mirror near tip on P10 (rarely terminal); small mirror on P9 often on gr.; black band on P5; often dark mark on P4; gray area quite dark from below
SECONDARIES
(in flight):
blackish above and below w/ very narrow pale fringe dark above and below w/ pale fringe as adult adult gray w/ broad white trailing edge about 1/2 bill length; strong contrast with gray area below
TERTIALS: very dark brown w/ crisp white edge; may have diffuse pale area near tip or small notches on sides dark gray w/ large pale marbled tips as adult but mixed w/ brown adult gray w/ large white crescent about 2/3 bill length
GREATER COVERTS: solid dark brown-black w/ obvious pale fringe and subterminal spot; more barred and spotted on inner feathers; appears as a dark bar in flight mottled adult gray and brown adult gray mixed w/ brown adult gray
LESSER & MED COVERTS: rather dark brown w/ pale edges, creating a scaled look (very bold in young birds); muddy later in winter adult gray w/ dark subterm anchors adult gray mixed w/ brown adult gray
SCAPULARS: similar to med,les covs adult gray w/ dark centers as adult adult gray w/ little or no white crescent
BACK: similar to med,les covs adult gray w/ dark centers adult gray adult gray is med dark on graellsii, very dark on intermedius
RUMP: appears quite pale; white with some dark mottling white white white
TAIL: large black band w/ pale fringe; all but inner retri- ces w/ extensive irreg pale barring at bases; outer- most webs white w/ dark bands near tip large black subterm band w/ extensive marbled base; outermost webs white white w/ variable subterm marks, esp on inner retrices white

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