Distinguishing Characteristics

Breeding adult Seaside Sparrow, Chambers Co., TX, April

Juvenile Seaside Sparrow, Little Creek WMA, DE, 28 July 2004

Seaside Sparrow, Conaskonk Point, NJ, June

Small songbird, sexes alike in plumage. Total length (skins): males 13.2–14.7 cm, females 13.0–14.2 cm (Ridgway 1901). Except in melanistic groups (see Appearance: Molts and plumages, geographic variation), plumage weakly patterned. Dominant dorsal coloration in Basic plumage grayish olive (A. m. maritimus, n. and central Atlantic Coast), yellowish olive (A. m. mirabilis, Everglades), greenish olive (A. m. sennetti, Texas), brownish black (A. m. peninsulae, Gulf Coast), or black (A. m. nigrescens, e.-central Florida). Distinct yellow supraloral spot. Gray to black moustache stripe set off by white throat and pale buffy malar stripe. Wing-bars absent. Edge of wing at wrist yellow. Striped (gray, brownish black, black) on breast, sides, and flanks. Bill elongate conical, about as long as head, dusky black, or maxilla dark and mandible pale. Tail pointed. Rectrices narrow and acuminate; central feathers longer than outer ones, > 80% length of wing (A. m. maritimus). Wear affects color and pattern. Late summer birds very faded, feathers “clipped,” and plumage essentially patternless. Wing formula variable, but usually (A. m. maritimus) 9 < 8 < 7 > 6 > 5 > 4 > 3; or 9 < 8 = 7 > 6 > 5 > 4; primaries 5–7 longest, 9 < 3, producing rounded wing-tip.

Juvenile buffier than adult, with pale buff supra-loral stripe; lacking rufous patch in wing; sharply defined streaks on buffy undersides (Byers et al. 1995).

Most similar to Sharp-tailed sparrows (Ammodramus caudacutus and A. nelsoni). Adult Seaside larger, grayer, and less strongly marked on head and body; juveniles larger and browner than juvenile A. caudacutus, in which head and body are predominantly ochraceous buff.