Saltmarsh Sparrow

Ammospiza caudacuta

Order:
Passeriformes
Family:
Passerellidae
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Figure 2. Annual cycle of Saltmarsh Sparrow breeding, migration, and molt.

Thick lines show peak activity, thin lines off-peak activity. The lines for breeding and migration reflect average timing across range, but local peak and off-peak timing varies between northern and southern parts breeding range. Earliest migrants may be individual outliers. Molt initiation can vary depending on end of most breeding activity (primary sources: Hill 1965, Winder 2012; JSG, New York; WP, South Carolina; P. Pyle, molt, based on specimens. In New York, we found no evidence of body molt in early arrivals of local individuals on breeding grounds, latest April-early May; JSG banding notes). See text on migration chronology.

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Definitive Basic Saltmarsh Sparrow.

Small ground-foraging sparrow, sexually monochromatic with an elongated, conical bill and a moderately short tail with distinctive, attenuated rectrix tips. Adults have a conspicuous orange-buffy eyebrow and malar; crown with an often weakly defined central gray stripe bordered by dark brown lateral stripes streaked with black. Throat whitish, with or without incomplete lateral stripes. Typically, a buffy chest band is present in fresh plumage. Breast, sides, and flanks are strongly streaked. Definitive Basic Plumage recognized by uniform wing and tail feathers of high quality without molt limits.

© Brad Sale, South Carolina, United States, 12 November 2017
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Saltmarsh Sparrow (upper right) and Nelson's Sparrow (bottom left).

Saltmarsh Sparrow is distinguished from all variants of Nelson’s Sparrow by strongly contrasting buff breast band, more orange tone of face triangle, and more strongly dark-streaked underparts, among other features.

© Doug Gochfeld, New York, United States, 26 September 2017
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Saltmarsh Sparrow.

Typically, a buffy chest band is present in fresh plumage, but this band bleaches with feather wear and can become quite pale. In both conditions (fresh and worn), the band contrasts strongly with the triangle pattern on the head, and note also the distinct breast streaking. These features help separate Saltmarsh from Nelson's Sparrow.

© Ryan Schain, Massachusetts, United States, 27 June 2017
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First Alternate Saltmarsh Sparrow.

Back feathers are a dark olive brown with scapulars and interscapulars broadly edged with buffy white, making conspicuous streaks. Note the three generations of tertials (juvenile, formative, and first alternate) and worn primaries, indicating age of this individual.

© Jason Denesevich, New Jersey, United States, 20 April 2017
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Formative Saltmarsh Sparrow.

Eyebrow and malar stripe broad, sharply defined, and dull ochre, with malar stripe curving upward behind gray ear coverts, separated from eyebrow stripe by a narrow dark brown or blackish postauricular stripe. Molt limit between replaced formative tertials and more-worn juvenile secondaries identified Formative Plumage; the bolder buff-orange wing bar may also be indicative of this plumage.

© Evan Lipton, Rhode Island, United States, 27 September 2017
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Formative Saltmarsh Sparrow in flight.

Marginal wing coverts in carpal area are pale yellow; remiges brown; greater secondary coverts edged with buff making an indistinct wing-bar. Retained juvenile primaries, primary coverts, and distal secondaries, contrasting with the replaced formative greater coverts and tertials, indicate Formative Plumage in October.

© Tom Johnson, New Jersey, United States, 12 October 2017
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Juvenile Saltmarsh Sparrow.

Juvenile plumage is a rich buffy color that is brightest on the eyebrow, malar stripe, and foreneck outlining the dusky ear coverts. Sides of neck, breast, and flanks are streaked with brown. Wing coverts and tertiaries broadly edged with yellowish buff, secondaries with russet, primaries and their coverts greenish, tinged olive gray, alula with white.

© Jonathan Eckerson, Massachusetts, United States, 18 August 2017
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Juvenile Saltmarsh Sparrow.

Back is streaked with brown. Crown and wings nearly black; wing coverts and tertiaries broadly edged with yellowish buff. Tail olive brown, indistinctly barred, without white.

© Jeff Hullstrung, Connecticut, United States, 28 July 2017
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Figure 3. Abnormal distribution of leucistic feathers in Saltmarsh Sparrow in Connecticut.

Photo credit: C. Gjerdrum.

A small sparrow (total length 12–13 cm, wing chord 53–59 mm, mass 14–17 g) of tidal marshes in the eastern U.S. Sexually monochromatic with an elongated, conical bill and a moderately short tail with distinctive, attenuated rectrix tips. Breeding and nonbreeding plumage similar, although feather wear weakens patterns. Southern populations darker on average than northern ones, with main transition in south-central coastal New Jersey.

Adult. In Definitive Basic and Definitive Alternate plumages, the head is mostly brown with conspicuous orange-buffy eyebrow and malar region that curves upward behind the dingy gray auricular patch creating a strong triangle on the side of the head; a black post-ocular line separates the eyebrow from the post-auricular area; crown dark brown, often with a weakly defined central gray stripe. A gray hindneck collar extends to the side neck and separates the crown pattern from that on the dorsal body. Upperparts, predominantly olive-brown, with whitish (often buff-tinged) stripes on the scapulars. Throat whitish, with or without incomplete malar stripes. Breast buff when fresh or white when worn, with band of dark streaks that continue down sides and flanks; the streaks are browner in northern birds, blacker in southern ones. Tertials (inner 3 secondaries) are fringed buff, with olive-brown (northern populations) to blackish (southern populations) centers. Ground color above can become quite dusky at the south end of the species’ distribution, and ventral stripes quite blackish. Basic and Alternate plumages are similar in intrinsic color but differ in appearance, primarily through wear of basic feathers.

Juvenile. Similar to adult but strongly marked above and below with buffy tones. Crown blackish with darker streaking and with weakly developed medial stripe; face pattern less distinct, with auricular browner; back and scapulars dark-centered, broadly edged with buff; underparts buff, heavily streaked dusky, the buff strongest on the breast and sides, weakening to whitish on lower abdomen. Following Juvenile Plumage, first-year birds (Formative and First Alternate plumages) are similar in appearance to adults but can be identified by retained juvenile feathers in the wing.

Bill: conical-elongate, maxilla blackish to dusky horn color, mandible paler. Legs light brownish pink to pale brownish. Tail acuminate at feather tips, > 80% of wing. Mean length, males 12.7 cm, females 12.4 cm. Wing tip rounded, typical wing formula p9 < p8 ≥ p7 > p6. Geographic variation: currently regarded as polytypic, characterized by weak step-clinal (south-central New Jersey) transition from paler, browner northern birds and darker, blacker southern ones. Recent molecular data, however, do not support distinct subspecies differentiation (J. Walsh, unpublished data). Extreme individuals can be distinguished with care.

Similar Species

The Saltmarsh Sparrow is most similar in color and pattern to Nelson’s Sparrow, which is geographically variable. Saltmarsh Sparrow is distinguished from all variants of the Nelson’s Sparrow by a combination of characters that are detectable in the field: strongly contrasting buff breast band from more orange tone of face triangle; more strongly dark-streaked underparts from central breast to flanks (rarely approached by strongly marked Nelson’s Sparrow from the northern plains); dark streaking in posterior supercilium; buff or off-white, less distinct scapular stripes (more grayish in Maritime Nelson’s Sparrow A. n. subvirgata and whiter, more conspicuous in interior/bay members of the species); darker, ‘colder’ olive-brown dorsal ground color (grayer in Maritime Nelson’s Sparrow, more golden, ‘warmer’ in interior birds); and more elongate conical bill on average. In the hand, bill is longer (nares to tip 8.3–10.1 mm vs. 7.8–9.4 in Nelson's Sparrow) and the longest primary to the longest secondary on the folded wing is shorter (0–7 mm vs. 5–12 mm in Nelson's Sparrow). Shape of head not diagnostic as feathers can be flattened or elevated at will depending on motivational state and ambient temperature. Hybrids from southwestern coastal Maine often express a mosaic of characters from the dull pattern and subdued colors of Atlantic (Acadian) Nelson’s Sparrow to strong colors and patterns of Saltmarsh Sparrow. Pure-bred Saltmarsh Sparrows in the New England hybrid zone (Systematics: Related Species) cannot always be distinguished from back-crossed hybrids bearing Nelson's Sparrow genes using plumage and morphological attributes in the absence of genetic information. Many hybrids are cryptic and appear to be typical individuals of either species. Other hybrids do mirror their genetic admixture, which may reflect more back-crossed genetic loci in such individuals (1).

Compared with generally similar Seaside Sparrow, Saltmarsh Sparrow is smaller with a slightly more slender bill, browner above, with a stronger, orange-toned pattern on side of head (bright color on head of Seaside Sparrow is mainly concentrated in the anterior supercilium), and more strongly streaked below, contrasting with the grayer, more subdued streaking of Seaside Sparrow. Seaside Sparrow is notably vocal and utter easily-learned calls and song in contrast to the quiet, less vocal Saltmarsh Sparrow.

LeConte’s Sparrow (A. leconteii) also is broadly similar in color and pattern, but is slightly smaller on average and has a shorter, more conical bill. Best distinguished from Saltmarsh Sparrow by strong, pale mid-coronal stripe, a noticeable malar stripe, a purple-streaked nape, and distinct white edges to tertials. Song Sparrow (Melospiza melodia), which occurs at the edges of salt marshes is larger, longer-tailed, lacks orange tones, and has more extensive, blurrier streaks. Savannah Sparrow (Passerculus sandwichensis) is smaller and paler, also lacks orange, has a smaller bill, and is generally more heavily streaked. See Pyle and Sibley (2), Sibley (3), and Pyle (4) for the identification of juveniles.

Detailed Description

Saltmarsh Sparrow has 9 functional primaries (numbered distally, from innermost, p1 to outermost, p9), 9 secondaries (numbered proximally from outermost s1 to innermost s9 and including 3 tertials, s7 to s9 in passerines), and 12 rectrices (numbered distally, r1 to r6, on each side of the tail). Geographic variation in appearance is slight and somewhat clinal. The following plumage descriptions pertain to the northern subspecies A. c. caudacuta unless noted; see Systematics: Geographic Variation for specifics on geographic variation in this species. No geographic variation in molt strategies has been reported.

Plumages

See Molts for molt and plumage terminology. The following is based primarily on detailed plumage descriptions of Dwight (5), Ridgway (6), Woolfenden (7), Pyle and Sibley (2), Byers et al. (8), Rising (9), and Sibley (3); see Pyle (4) for age-related criteria. Sexes show similar appearance in all plumages. Definitive plumage is essentially assumed following the Prejuvenile Molt.

Natal Down

Present April–June. Rand (1929) described the down as varying from brownish black on head to mouse gray on rump; absent from ventral and crural tracts, and unevenly distributed on capital, dorsal, humeral, and femoral tracts, and on greater wing coverts. Heaviest on sides of head and rump. Dwight (5) described down as “grayish wood-brown.” Woolfenden (10) depicted and quantified the number of white neossoptiles in each feather tract, which are present primarily on posterior end of ventral tract.

Juvenile (First Basic) Plumage

Present primarily June–August. Rich buffy, brightest on eyebrow, malar stripe, and foreneck outlining dusky ear coverts; back, sides of neck, and flanks streaked with brown; crown and wings nearly black; wing coverts and tertiaries broadly edged with yellowish buff, secondaries with russet, primaries and their coverts greenish, tinged olive gray, alula with white. Tail olive brown, indistinctly barred, without white.

Formative Plumage

"First Basic" or "Basic I" plumage of Humphrey and Parkes (11) and some subsequent authors; see revision by Howell et al. (12). Present primarily September–February. Similar to Definitive Basic Plumage (possibly more buffy on average, especially ventrally) but differs in having retained juvenile feathers in the wing, these feathers of less quality and contrasting with more closely knitted replaced, formative, feathers. Molt extent varies but in most populations, the inner 2–6 secondaries, outer 5–6 primaries, and sometimes outer 1–2 primary coverts are replaced, contrasting with the retained outer 3–7 secondaries, inner 3–4 primaries, and most or all primary coverts retained. Retained juvenile primary coverts are relatively brown and abraded, with little or no pale edging, contrasting markedly with the outer 1–2 primary coverts (if replaced) and greater coverts (4). Note that replacement of can occur on summer and/or winter grounds; before the Preformative Molt all juvenile wing and tail feathers Especially the outer primaries and rectrices) are relatively narrow, abraded, and worn.

First Alternate and Definitive Alternate Plumages

Present primarily March–August. Despite extensive molt, plumage characters very similar to those of Formative and Definitive Basic Plumage, indicating that molt has evolved to replace feathers (due to harsh and open environments) and has been unshaped by adaptation for display plumage. Age determination criteria similar to those between Formative Plumage and Basic Plumage except that molt limits in upperwing and/or completely replaced rectrices may occur in both age groups; but retained juvenile outer primaries and primary coverts become increasingly worn, frayed, and bleached during first spring and summer, differing more from better-maintained retained basic feathers in older birds.

Definitive Basic Plumage

Present September–February. Lateral crown dark brown, streaked black, and with a poorly defined grayish or brownish-gray median crown stripe; eyebrow and malar stripe broad, sharply defined, and dull ochre, the malar stripe curving upward behind the gray auriculars, but separated from eyebrow stripe by a narrow dark brown or blackish post-auricular stripe; nape with gray collar; hind neck bronzy brown; back feathers dark olive brown with scapulars and interscapulars broadly edged with buffy white, making conspicuous streaks; rump olive brown with darker brown streaks; uppertail coverts with dark centers; rectrices dark brown along shafts, and paler along edges, but without white; each rectrix sharply pointed. Upperwing marginal lesser coverts (in carpal area) pale yellow; median and greater coverts black-centered with broad rufous to cinnamon fringes forming two inconspicuous wing bars; primary coverts dusky-brown edged with ochre; remiges brown. Throat white or light ochre; underparts mostly white, but with chest, sides, and flanks tinged yellowish buff when fresh, sharply and usually distinctly streaked with dusky brown or black; underwing coverts whitish except bright yellow in carpal area.

Definitive Basic Plumage separated from Formative Plumage by having primaries, secondaries, primary coverts, and greater coverts uniform in quality and freshness, not contrasting in feather quality with juvenile feathers as in Formative Plumage (4).

Plumage Abnormalities

See Figure 3. Partial albinism (13, 14) known in species. Albinism encountered in Long Island Sound near New York City in late 1960s and early 1970s, consists of white-spotting (14, JSG); white feathering found primarily in adults and could be due to the effects of pollution in study area at this time (15). Wayne (13, 16) collected about 1 pure albino and 25 partial albinos between 1900 and 1921, and 2 more in 1924 in Mount Pleasant, South Carolina. Partial albinos also described from Massachusetts (7), and Ross (17) lists other records.

Molts

Molt and plumage terminology follows Humphrey and Parkes (11) as modified by Howell et al. (12, 18). Saltmarsh Sparrow exhibits a Complex Alternate Strategy (cf. 12, 19), including complete prebasic molts, and partial-to-incomplete preformative and prealternate molts in both the first and later molt cycles (20, 5, 21, 22, 23, 10, 7, 4, 24; Figure 2).

Prejuvenile (First Prebasic) Molt

Complete, primarily May–July, in the nest. Feather papillae of Juvenile Plumage visible by the second day, but feathers remain sheathed until the seventh day (10). By day 2, visible feather papillae continue to develop and new papillae appear; by days 3–4, papillae prominent on all feather tracts; by day 6, developing remiges and head feathers still sheathed but tips of other body feather tracts unsheathed; by day 7, remigial sheaths become gray (previously dark blue) begin to slough off; by day 8, young well-feathered at this age except on coronal region of capital tract. Eighth primary exhibited little growth until day 2, but afterward (days 4–11) growth nearly linear. Rectrix growth minimal until day 6 when feathers about 1.0 mm, but afterward feathers elongate more rapidly to about 9.5 mm on day 11 (10). Duration of Prejuvenile Molt among individuals probably ca. 10–12 d, with outer primary and rectrix growth completed following fledging.

Preformative Molt

"First Prebasic" or "Prebasic I" molt of Humphrey and Parkes (11) and some subsequent authors; see revision by Howell et al. (12). Partial to incomplete, primarily July–October on or near breeding grounds but some individuals could complete molt in November-December on winter grounds as in LeConte's Sparrows (2); study needed. Includes body plumage, upperwing secondary coverts, 2–3 tertials (and sometimes s6), and no to all rectrices, but no primaries, primary coverts, or other secondaries (24).

First Prealternate and Definitive Prealternate Molts

Partial to incomplete, March–May, primarily on winter grounds but may continue during northbound migration or on breeding grounds. First and subsequent prealternate molts similar in timing and extent, the definitive molt perhaps averaging slightly more extensive (24). Includes most to all body plumage and wing coverts (some outer greater coverts can be retained), 2–3 tertials (and sometimes s6) and all rectrices, but no primaries, primary coverts, or other secondaries. Reported as complete by Woolfenden (7) and complete in adults by Forbush (22) but this apparently incorrect (20, 24). Prealternate Molt appears to differ in extent from that of Nelson's Sparrow (4, 24), at least inland-breeding populations of that species, where outer primaries can be replaced. Further study is needed to elucidate molt extents in these species.

Definitive Prebasic Molt

Complete, primarily July–October, on or near breeding grounds, although study is needed on the relationship between breeding areas and molting grounds. On 2 study areas in New York, molting birds remained on breeding marshes but molting occurred in suitable feeding (tall, seeding S. alterniflora) and roost patches (JSG, unpublished data). Primaries replaced distally (p1 to p9), secondaries replaced proximally from s1 and proximally and distally from the central tertial (s8), and rectrices probably replaced distally (r1 to r6) on each side of tail, with some variation in sequence possible.

Bare Parts

Bill and Gape

In hatchlings, gape pinkish with yellow flanges, bill becoming darker with age. In adults, upper mandible dark horn colored, generally paler toward the base and ventrally; lower mandible paler, darker terminally; gape pinkish.

Iris

Brown.

Legs and Feet

Pinkish in hatchlings, becoming olive-brown in adults or sometimes remaining pinkish (JSG).

Linear Measurements

Wing Length

In New York, male A. caudacuta: wing chord mean 57.1 mm ± 0.062 SE (range 54.0–61.0, n = 369); female 53.6 mm ± 0.080 SE (range 51.0–57.0, n = 199). Sex estimated in fall juveniles based on nonoverlap range (> 58 mm for male; < 54 mm for female) was confirmed in all cases of banded returnees the following year (n = 16) (JSG, unpublished data).

Wing Area

No information.

Wing Span

No information.

Mass

Body Mass and Composition

Body mass (median, first and third quartiles, and range shown) are lower in the southern portion of the species’ range (assigned to populations of diversa) than in the north (assigned to nominate caudacuta), reflecting clinal variation in this character along with plumage color (25: Figure S1). In New York, male A. caudacuta, May–August: body mass mean 20.0 g ± 0.064 SE (range 17.8–24.1, n = 249); female May–August: 18.4 g ± 0.124 SE (range 15.4–22.5, n = 166); male, September–October: 19.9 g ± 0.128 SE (range 17.1–23.8, n = 120); female, September–October: 18.1 g ± 0.268 SE (range 15.8–22.1, n = 33) (JSG, unpublished data).

Fat (abdominal and furcular) scores average lower in summer in both males and females than in winter. Summer fat scores (across 2 fat depots) averaged about 1.2 in females and about 0.3 in males, representing little to no energy reserves carried by birds at this season, and rose to about 2.0 in both sexes in winter. Pectoral muscle scores ranged between 3.0–3.5 (on a 0–6 scale), a little lower in summer than in winter, but similar between sexes (26). No information on composition of body.

Recommended Citation

Greenlaw, J. S., C. S. Elphick, W. Post, and J. D. Rising (2018). Saltmarsh Sparrow (Ammospiza caudacuta), version 2.1. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.sstspa.02.1