Appearance

Descriptions based on Bent 1921, Oberholser 1974, Schreiber and Schreiber 1980, Grant 1986, and examination of specimens by JB and M. Gochfeld.

Hatchlings

At hatching covered with soft down, a light wood brown or pale gray base color, tinged with dark brown, brownish black, or cinnamon; underparts lighter colored but not white. Mottled on sides with dull black or clove brown. Head and back heavily mottled or spotted with black or dusky splotches.

Juvenal Plumage

Prejuvenal molt completed before young fully grown (e.g., early to mid-Jul). Feathers appear first on scapulars, then remiges, then underparts and rectrices, and finally crown. Head gray brown, paler on forehead, lores, chin, and throat, and darker on ear-coverts, rear crown, and nape. Black crescent in front of eye and whitish crescents above and below eye. Mantle, scapulars, lesser- and median-coverts, and tertials dusky brown, broadly tipped and margined with cinnamon buff or pinkish buff, producing a scaly appearance (Bent 1921, Grant 1986). Greater-coverts gray brown, edged whitish; secondaries blackish narrowly edged and broadly tipped white; primaries and primary-coverts blackish with primaries increasingly edged gray and tipped white toward inner feathers. Sides of neck, breast, and flanks gray brown; belly, undertail-coverts, and rump dull white. Tail grayish with feathers edged whitish on inner webs, broad black subterminal band that extends to outermost tail feathers, and narrow dull white or buffy terminal band.

Basic I Plumage

Prebasic I molt partial, completed Oct–Nov. Does not include Juvenal remiges and rectrices and coverts of outer wing.

Similar to Juvenal plumage except head becomes paler and more grayish with more extensive white on forehead, crown, lores, and throat; mantle, scapulars, neck, breast band, and flanks become more grayish, and variable number of new gray coverts on inner wing. Plumage with less white and more mottling in wing-coverts than Definitive Basic.

Alternate I Plumage

Prealternate I molt partial, occurs Feb–Mar. Does not include remiges or rectrices.

Similar to Basic I except gray on head less extensive, or head may have black hood of variable extent; remainder of plumage paler or faded, and white areas more extensive. This plumage includes feathers generated by Prejuvenal, Prebasic I, and Prealternate I molts.

Basic II Plumage

Prebasic II molt complete, occurs Jul–Nov (mainly Aug–Oct).

Head, neck, and underparts white with dark “saddle” (variable in extent) extending from eye through ear-coverts and around rear crown and nape, black crescent in front of eye, white crescents above and below eye, and gray wash on sides of neck, sides of breast, and flanks. Upperparts, including wing, mouse gray or slate gray. Outermost 4–5 primaries and their coverts black with black subterminally on next few inner primaries. Scapulars, tertials, secondaries, and primaries (except for outermost primary) tipped white. Variable number of secondaries with blackish on outer web forming indistinct “secondary bar.” Rump white. Tail white, sometimes with gray base, and with narrow blackish subterminal band that does not extend to the outermost or central rectrices.

Alternate II Plumage

Prealternate II molt partial, similar to Prealternate I molt, occurs Feb–Mar; occasionally in Apr.

Similar to Basic II plumage except head with extensive or complete black hood, underparts largely without gray wash, and white tips on outer primaries reduced or completely worn away.

Definitive Basic Plumage

Definitive Prebasic molt complete, occurs from late summer to Oct. Schreiber and Schreiber (1979) reported molt scores for primary feathers in Florida (n = 136): Feb–Apr = 0 for both sexes; males, May = 7 (range 1–15), Jun = 3 (1–7), Jul = 10 (4–21), Aug = 25 (8–41), Sep = 34 (21–45), Oct = 39 (33–50); females, May = 0, Jun (no samples), Jul = 8 (4–12), Aug = 25 (6–37), Sep = 34 (30–0), Oct = 44 (40–47). A molt score of 50 indicates all new feathers in 1 wing, whereas 0 equals all old feathers. Primary molt begins as breeding season ends, and requires 3 mo; secondary and rectrix molt somewhat later and proceeds later in fall; all adults molting black head feathers by Aug (Schreiber and Schreiber 1979).

Head and underparts white. Gray streak behind eye often widening into a small patch on ear-coverts which may extend over rear crown. Small black crescent in front of eye and white crescents above and below eye. Sides of neck and sides of breast clouded pale gray. Upperparts, including wings, mouse gray to slaty gray with white rump. Outermost primaries (P8–P10) black with chocolate brown toward base of inner web of P6–P8; P1–P4 and all secondaries slate gray broadly tipped with white. Primaries broadly tipped with white in decreasing amounts toward the outermost feather which is entirely black. Outermost 1–2 greater primary-coverts sometimes with black. Tail white.

Definitive Alternate Plumage

Definitive Prealternate molt partial, includes body feathers, particularly head and neck, but not remiges or rectrices; occurs Feb–Apr.

Entire head black to sepia, forming a “hood.” Hood extends farther down neck than on similar Franklin’s Gull. White crescents above and below eye but not as thick as in Franklin’s Gull. Remiges as in Definitive Basic plumage, but white feather tips on outer primaries now much reduced in size or completely absent through wear. Upperparts mouse gray to slaty gray, becoming dark mouse gray on posterior portion. Rump and tail white. Underparts white. Breast often slightly tinged with pink, but this color fades rapidly as season progresses. Underwing-coverts all white, except greater underwing-coverts medium gray.

Almost all breeding adults retain completely black head until they leave the colony, and some retain it for a few weeks after leaving.

Bill And Gape

Bill in hatchlings and Juvenal plumage dull brown. Alternate I bill black, brownish black, or olivaceous black, tinged with red and tipped with dull white; gape seashell pink or dull orange, and remains so until breeding. Adult breeding (Definitive Alternate) bill maroon or dark brownish, terminally a deep red, blood red, or carmine, with distinct brown spot or bar subterminally. Gape and corner of mouth deep carmine or reddish orange while breeding. Adult nonbreeding (Definitive Basic) bill blackish. In Caribbean, breeding adult bill darker red.

Iris

Brownish black becoming dark brown in adults.

Eye-Ring

Black in Alternate I; whitish flecked with dull or hair brown in Basic I; all white in Definitive Alternate.

Legs And Feet

Dull dark brown in hatchlings, olive in Juvenal plumage, black in Alternate I plumage. Reddish to bright red in breeding adults (Definitive Alternate), becoming reddish black by end of breeding season and black during nonbreeding season (Definitive Basic).