(schistisagus)
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Slaty-backed Gull (schistisagus) |
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IMAGES:
DESCRIPTION:
First Cycle
Second Cycle
Third Cycle
Adult
SLATY-BACKED GULL (24"-27"; 52"-54") schistisagus
| BILL SHAPE: fairly thick and straight, may appear stubby; 4-5x eye diameter; gonydeal angle small. to moderate. | ||||
| HEAD SHAPE: rounded to low sloped forehead, flat crown w/ squared-off rear crown | ||||
| WING EXTENSION: about bill length | ||||
| POSTURE/HABITS: often very bulky or wide-bodied (like a goose from behind); may appear long-necked when standing | ||||
| FIRST WINTER | SECOND WINTER | THIRD WINTER | ADULT WINTER | |
| BILL COLOR: | black w/ pinkish base to lower mandible and a touch at base of culmen; pale tip by summer | pale yellow to black w/ pink base to lower mand; variable dark subterm band | ... | ... |
| LEG COLOR: | bright pink or dark pink | bright to dark pink | bright to dark pink | bright pink, even reddish |
| IRIS/ORB RING: | dark | often pale yellow | pale yellow | pale yellow or cream to light amber; orb ring red to pink |
| HEAD: | quite pale with dark gray smudge in front and immediately around eye; creamy brown blurred streaks on rear crown and nape | mostly white w/ light streaking on crown and aur edge; dark streaks on nape and neck side; dark smudge around eye | same as adult | obvious dark gray smudge around eye, extending more in front and behind; otherwise variable thin brownish streaks over aurs, rear head, and neck; many white-headed by late Jan |
| UNDERPARTS: | light blotching on breast, becoming nearly solid and darker on belly; undt. coverts barred | breast pale and blotchy; belly blotchy or solid dark; undt covs may have pale bars | mod blotching on lower breast and belly | white |
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PRIMARIES (folded): |
med. dark brown, not black, w/pale crecents like Thayers but sometimes larger, w/ pale edge extending along upper (inner) edge of the feathers | med dark brown, not black, w/ pale cresents or tiny A-spots | as adult w/ A-spots, but spots may be smaller | black w/ A-spots; A7 larger than eye; A8-10 same or smaller than eye |
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PRIMARIES (in flight): |
dark brown on outermost Ps with slightly pale window on inner Ps (becoming more obvious in late winter), w/ dark subterminal spots in window; very pale or silvery from below, with thin dark trailing edge and dark P9-10 | outer Ps dark brown, inner Ps virtually white above; pale silvery below, w/ outer Ps slightly darker | usually shows small mirrors and white tongues of adult | large mirror on P10; often small mirror on P9; large white tongues on P6-7 and usually P8, called a "string of pearls", obvious from above and below; black parts are dark gray below |
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SECONDARIES (in flight): |
solid dark brown above; silvery from below | med brown w/ large pale fringe and edges, creating weak dark bar above; pale silvery from below | ... | adult gray w/ broad white trailing edge, about 3/4 bill length; may show thin white skirt when perched |
| TERTIALS: | moderate dark brown (slightly lighter than Ps), w/ broad pale tip or subterm chevron; may show pale edges | med brown w/ irregular but heavily mottled tips | adult gray w/ white tertial crescent about 1/2 - 3/4 bill length | adult gray w/ large white crescent, about 3/4 bill length |
| GREATER COVERTS: | variable; fairly solid med g-b (slightly lighter than Ts) on darker birds; fading to white quickly, often showing 2 rows of faded dark spots | solid rather pale g-b w/ fine internal marbling near tips; fading to white by summer | muddied adult gray and brown | adult gray |
| LESSER & MED COVERTS: | creamy white w/ dark subterminal anchors, giving a pale look to upperwing; prone to fade | largely pale cream w/ irreg small dark subterm anchors or shafts; prone to fade | muddied adult gray and brown | adult gray |
| SCAPULARS: | pale gray with thin black shaft lines and variable pale tip; not checkered | like M&L covs or w/ some adult gray; may show white crescent | as adult but with smaller white crescent | adult gray w/ white crescent about 1/2 bill length |
| BACK: | same as scapulars | adult gray or like muddied 1W | as adult | adult gray is very dark gray, darker than Vega |
| RUMP: | variable, mottled w/ dark; pale by summer | white | white | white |
| TAIL: | almost solid dark brown; pale fringe; fine white bars on outermost webs; irreg pale bars at base of outer retrices | solid dark brown w/ pale fringe and slighly mottled pale bases to outer retrices w/ pale bars at base of outermost webs | mostly blackish w/ white fringe and extensive white mottling to bases, producing jagged look | white |