Appearance

Figure 7. Annual cycle of breeding, migration, and molt for the Seaside Sparrow

Adult male Seaside Sparrow, Fishing Creek WMA, MD, 28 July 2004

Seaside Sparrow, Conaskonk Point, NJ, June

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

Adults and Juveniles eating leaves of halophytes and Spartina seeds, Texas.

Seaside Sparrows have 9 functional primaries, 9 secondaries (including three tertials), and 12 rectrices. Wings are rounded and tail is pointed. Geographic variation in appearance moderate. The following plumage-aspect descriptions pertain to the nominate subspecies A. m. maritimuss; see Systematics: Geographic Variation for variation in up to six other recognized subspecies along the Atlantic and Gulf of Mexico coastlines of North America. Geographic/systematic variation in molt strategies has been reported (Pyle 1997a, 1997b; see below).

Molts

Molt schedule applies to A. m. maritimus unless otherwise noted, based in part on plumage inspection in captured birds (Long I., NY). Molt and plumage terminology follows Humphrey and Parkes (1959) as modified by Howell et al. (2003, 2004). Seaside Sparrow appears to exhibits a Complex Alternate Strategy (cf. Howell et al. 2003), including complete prebasic molts, a partial or incomplete preformative molt, and limited prealternate molts in at least some individuals of both first and definitive cycles (Stone 1896; Dwight 1900; Woolfenden et al. in Bent 1968; Oberholser 1974; Pyle 1997a, 1997b; Fig. 7). A limited auxiliary preformative ("first presupplemental") molt has also been suggested (Pyle 1997a) but this "molt" may simply represent continued activation of follicles during protracted post-fledging prejuvenal molt as fledgling develops, rather than a separate molt involving replaced juvenal feathers.

Prejuvenal (First Prebasic) Molt

Complete, May-Jul, primarily or entirely in the nest. Papillae visible by d 1 in most feather tracts. Developing juvenal feathers, which begin emerging from sheaths on body by d 7, displace natal downs; some downs temporarily remain attached to distal tips of juvenal feather shafts. Molt complete or nearly so by d 9 (see Breeding: Young Birds: Growth and Development for further details) but see also above regarding auxiliary preformative molt.

Preformative Molt

("first prebasic molt" of Pyle 1997a and previous authors)

Partial to incomplete, Jul-Dec, on or near breeding grounds but completes on winter grounds in migratory populations. Most young birds in New York replace all juvenal feathers except remiges and their coverts before leaving natal area in late fall; these presumably complete molt (flight feathers; see below) on wintering grounds, as late as December in S. Carolina (WP). Considerable individual variation in timing of molt (usually starts by late August in New York), depending on timing of nest departure and (perhaps) geographical location. In nw. Florida, 90% of HY birds have not completed remigial molt until 1 Oct. In most subspecies (see below), preformative molt eccentric in most birds (ca. 77%), including 5-6 outer primaries (among p4-p9), occasionally 1-2 outer primary coverts, the tertials, up to 3 additional proximal secondaries, and all 12 rectrices. Extent apparently differed in Dusky Seaside Sparrow (nigrescens) being partial and including most to all secondary coverts but few or no other flight feathers (or, possibly, being complete). Prefomative Molt in Cape Sable Sparrow (mirabilis) may or may not be similar; study needed.

Definitive Prealternate Molt

Absent to partial, Mar-Apr, on or near wintering grounds in migratory populations. Formerly reported as absent (Dwight 1900), plumage-aspect changes between fall and spring based on wear, but specimen examination indicates facultative prealternate molt of at least some wing feathers, probably necessitated by feather damage caused by abrasive salt-marsh environments. In most subspecies can include up to 5 inner greater coverts, and 1-3 tertials in 33% of birds (Pyle 1997b); extent of body feather replacement not known (study needed) but many basic feathers retained and subject to wear (see Alternate Plumages, below). First (Definitive) and subsequent prealternate molts similar in timing and extent, as far as known. Prealternate molt may not exist in Dusky Seaside Sparrow (Pyle 1997a, 1997b).

Definitive Prebasic Molt

Complete, Jul-Sep, on or near breeding grounds. Primaries replaced distally (p1 to p9), secondaries replaced proximally from s1 and proximally and distally form the central tertial (s8), and rectrices probably replaced distally (r1 to r6) on each side of tail, with some variation in sequence possible. Usually begins mid to late Aug in New York, first half of Jul in nw. Florida; 90% completion date for adult remigial replacement: New York, 16 Oct; nw. Florida, 17 Sep. No differences noted in chronology of sexes.

Plumages

Following based primarily on specimen examination; see also detailed plumage descriptions of Ridgway (1901), Oberholser (1974), Byers et al. (1995), and Rising (1996). See Pyle and Sibley (1992) for details of juvenal plumage and Pyle (1997a) for age-related criteria. Feathers in all plumages subject to extensive abrasion, with wear, which distorts color and obscures patterns in breeding adults by late June in New York. Sexes show similar aspects in all plumages. Definitive plumage aspect essentially assumed following preformative molt.

Natal Down (Apr-Jul).

Hatchlings naked except for thin tufts of grayish brown (upperparts) to whitish (posterior ventral tract) natal downs in parts of all feather tracts (Woolfenden 1956). Down longest, most prevalent on upper body surfaces, nearly absent below. Worn only for few days in nest.

Juvenal (First Basic) Plumage (May-Aug).

Plumage aspect dominated by buff and olive tones; pattern relatively indistinct on most parts of body, except for back and ventral streaking. Body feathers filamentous and subject to rapid wear. Forehead and crown olive brown streaked finely with black; nape olive brown, unstreaked; face with moderately distinct grayish buff auriculars (ear patch) and buffy superciliary which is yellower in front of eye (supraloral) than behind it; cheek and postauricular area buff, former bounded below by indistinct dusky moustachial stripe. Back, scapulars, and rump olive brown streaked with blackish; streaking on back moderately heavy (produced by alignment of dark centers of many back and scapular feathers) whereas rump streaking short, narrow. Rectrices olive brown, darker along shaft. Remiges and coverts dull brownish black, with no evidence of wing-bars; tertials 1 and 2 and innermost secondaries edged with rusty brown, median and greater secondary coverts edged with buff. Chin and throat white tinged with buff. Breast, sides, and flanks buff streaked variably with dusky; belly white, buffier under tail and on tibiae (Graber 1955, JSG). Geographical variation in color and pattern poorly known.

Formative Plumage (Sep-Mar).

Aspect similar to that of Definitive Basic Plumage (below). Birds in formative plumage separated from those if definitive basic plumage by molt limits among primaries and secondaries in most birds, juvenal inner primaries and outer secondaries retained, bleached and abraded, contrasting with fresher and darker, replaced formative inner secondaries and outer primaries. First-cycle individuals not replacing primaries or secondaries can be identified by similar contrasts between juvenal and formative wing coverts, among greater coverts or between greater and primary coverts (Pyle 1997a). These criteria apparently invalid for ageing Dusky Seaside Sparrow.

First and Definitive Alternate Plumages (Apr-Sep).

Aspect similar to that of Definitive Basic Plumage (below). Breeding aspect at all ages affected by wear of formative or basic feathers along with replacement of at least some wing feathers during prealternate molt. By late spring and early summer in New York, abrasion at barb tips of at least some body feathers advanced, resulting, for example, in reduction or loss of buff wash across breast and some olive tones on dorsum, thus emphasizing grays above and white below. Criteria for identifying individuals in first-alternate plumage by molt limits in wing similar to those for birds in Formative Plumage (above).

Definitive Basic Plumage (Sep-Mar).

Dorsum predominantly grayish olive, indistinctly marked, and underparts whitish with diffuse gray streaks and strong buffy wash across breast and on sides and flanks. Crown with indistinct, diffuse central grayish stripe bounded laterally by broad brown stripes and streaked narrowly with black; lores dusky, yellow supraloral spot blends to olive-green over eye (often thinly edged above by short line of white), composite forming poorly defined eyebrow; ear patch gray to blackish outlined below by narrow white or pale buff malar stripe which may curve partly behind auriculars as dusky buff area; broad moustachial stripe gray framed by pale malar and white throat and chin; short postauricular stripe blackish, variably developed. Hindneck “bronzy-brown” or olive forming collar, shading to grayish olive on side neck. Back feathers with dark grayish olive to blackish centers and inner webs, and grayish exposed outer webs which in some individuals produce diffuse or indistinct pale (grayish) and dark back stripes (disappear with wear); rump paler than back; uppertail coverts olive grayish streaked with black. Ground color of underparts whitish to grayish white, browner on flanks, with indistinct gray stripes on breast (occasionally diffuse spot center breast), sides, and flanks; central abdomen unmarked; undertail coverts pale buff. Tibia pale brown. Wings lack wing-bars, remiges blackish (fresh) to brownish black, exposed webs of greater secondary coverts and innermost tertial cinnamon to cinnamon brown, edge of wing at wrist yellow. Tail about 20% shorter than wing; rectrices attenuated at tips, inner ones longer than outer, with brownish black shaft streak and paler (dusky) webbing, margined along edge of outer vane by olive-greenish and crossed by dark bars when fresh, confluent with shaft streaks. Individuals in Definitive Basic Plumage separated from those in Formative Plumage (above) by lack of contrasts among feathers of wing, the basic flight feathers uniformly darker and comparatively fresher than juvenal feathers retained in formative plumage.

According to McDonald (1985), the hypothesis that pale and dark individuals occur within the same population (Griscom 1944, Funderburg and Quay 1983) is unsupported. The sparrow’s plumage has faded significantly by breeding season, and early researchers based their conclusions on comparing faded with fresh specimens. McDonald and H.W. Kale (in McDonald 1988) examined 1,318 specimens, most collected in fall and winter. McDonald concluded that the use of the terms pale and dark phases (Griscom 1944) was misguided, and was based on failure to consider seasonal and age-related variation. Overall, populations of Seaside Sparrows along Atlantic and Gulf coasts are characterized by lighter-colored birds at 1 end of range (ne. U.S., s. Texas, respectively), and dark-colored birds at other end, and such variation is continuous (JSG; S. Carolina and Georgia).

Northeastern birds show high incidence of white-spotting in formative and basic plumages (Enders and Post 1971). Extent of white varies from single partial white feathers anywhere in plumage to extensive patches of white in almost every part of plumage. At Oak Beach, NY, 17% of 104 breeding individuals had white feathers. Among 214 museum specimens of adult A. m. maritimus, 4% had white-spotting. In contrast, only 0.4% of 246 adults collected from southeastern and Gulf Coast populations had any white (Enders and Post 1971).

Bare Parts

Bill And Gape

Bill often 2-toned in adults; tip, tomia, and ventral surface of mandible lightest. Dorsal area of maxilla jet black (color #89 of Smithe 1975) to dark grayish brown (#20). Mandible medium plumbeous (#87) or glaucous (#85). Gape can be fleshy and yellowish in Juvenile.

Iris

Brown (JSG).

Legs And Feet

Pinkish flesh in nestlings, becoming dark brownish olive (#129) or grayish horn (#91) when fully grown. Foot pads Prout’s brown (#121a).