SPECIES

Bar-tailed Godwit Limosa lapponica Scientific name definitions

Brian J. McCaffery and Robert E. Gill
Version: 1.0 — Published March 4, 2020

Plumages, Molts, and Structure

Plumages

Hatchlings

Natal down well developed at hatching. Coloring of chicks soft and blended warm buff and sepia; none of the markings clearly defined as in most small sandpipers (Gabrielson and Lincoln 1959). Following mostly from Bent 1929 and Brandt 1942 . Dorsal ground color, breast, lower throat, and sides of neck dull, pale pinkish cinnamon/buff (121D); forehead, eyebrow-stripe, and broad band behind wings (excluding center of back) paler, even whitish; crown brownish black (119) or mouse gray (Brandt 1942), with median strip of sepia (219); sides of head very pale pinkish cinnamon, slightly washed with brown; area around eye extensively white, but with narrow and broken sepia streak through eye and often with dark spot above ear; hindneck clouded fuscous (except upper, which is crossed by fuscous bar); back mottled fuscous with marks on wing and back tending to form concentric circles; upper throat and belly buffy-white; under tail drab to hair brown. Similar to downy young of other Limosa, except for dark line from bill to crown and lateral spot absent from hindcrown (Baicich and Harrison 1997).

Juvenile Plumage

Juvenile plumage generally similar to Definitive Basic plumage. Crown dark brown (119A) with narrow cream (54) feather edges. Broad buff (124) to white superciliary stripe, indistinctly streaked brown (119B); supercilia separated on forehead by narrow dark-brown streak and bordered below by dark-brown eye-stripe, which is narrow next to bill, becoming narrower at eye and broadening and becoming brown on ear coverts. Chin, throat, nape, and neck-feathers cream with some brown shaft streaks. Upperparts as in Definitive Alternate plumage but mantle and scapular-feathers more neatly and boldly variegated or speckled by buff edges and spots on edges of dark-brown feathers. Back, rump, and uppertail coverts darker brown with heavy off-white barring; brown shaft streaks and off-white bars near feather tips. Underparts mostly off white, with breast and flanks cream to buff. Bases of feathers of breast with dark-brown shaft streaks, giving mottled brown appearance with wear, especially on sides of breast. Hindflanks and lateral undertail coverts with 1–3 narrow brown subterminal chevrons. Tail (12 rectrices) as adult, but feathers barred buff across width, with faint rufous-brown (340) wash. Median- and greater secondary coverts of upperwing dark brown with 2 or 3 large buff terminal spots. Lesser-coverts black-brown (119) with narrow buff edges. Primaries (n = 11; P10 longest) and secondaries (17, including 6 tertials) black (89) with broader white fringes than in adult; inner-edge width of white on primaries used to separate juveniles from adults (Cronau et al. 1986). Tertials black with 4–6 large orange-buff (118) terminal spots on both webs (cf. just on inner webs of adult breeding). Under wing as in Definitive Alternate plumage but lesser and median underwing coverts light gray (86) with fewer submarginal flecks and streaks.

Basic I Plumage

Basic I plumage like Definitive Basic plumage but retaining old, very worn Juvenile feathers on back, rump, most of tail, inner upperwing coverts and remiges until at least Mar. Back and rump almost completely brown. Inner rectrices with regular markings, like adult (not regularly barred like Juvenile). Outer tertials old and very worn, showing traces of Juvenile plumage (buff spotting). With wear, inner upperwing coverts become notched at edges. Contrasting worn Juvenile and fresh nonbreeding feathers very different from uniformly fresh adult nonbreeding plumage. Second Prebasic molt (second calendar year) complete, primaries outward Jul–Oct; may start immediately after completion of first Prealternate molt, usually completed before breeding adults return south. Basic II plumage like Definitive Basic (see below) and not always separable; because usually attained before adults return, remiges and coverts generally more worn than in adults later in season (Barter 1989a).

Alternate I Plumage

Can be distinguished from adult breeding by retention of Juvenile underwing coverts and tertials, which become very worn and faded (cf. adult breeding plumage). New feathers of crown, nape, hindneck, and upperparts edged paler rufous brown (240) than in adult male breeding; breast and flanks varyingly mottled white and rufous brown with some subterminal brown barring to feathers on many individuals.

Definitive Basic Plumage

Forehead and crown streaked brown and off white. Broad, white superciliary stripe, speckled light gray-brown (119C) and bordered below by indistinct brown eye-stripe extending from bill to nape. Chin white. Throat and foreneck-feathers off white, with indistinct brown shaft streaks. Ear-coverts, sides of neck, nape, and hindneck streaked brown and pale gray-brown. Upperpart feathers (mantle and scapulars) gray-brown, becoming light gray-brown toward edges, with black-brown shaft streaks and narrow white tips when fresh. Back and rump as Definitive Alternate plumage (see below). Upper tail-coverts barred white and black-brown. Underparts (upper breast and upper flanks) light gray-brown with narrow white tips to feathers when fresh and dark-brown shaft streaks; when worn, shaft streaks visible on sides of breast. Lower flanks, sides of vent, and lateral undertail coverts white with some subterminal brown bars to feather. Rest of underparts white. Wing like Definitive Alternate (see below) but all secondary coverts fresh brown with black-brown shaft streaks and white fringes. Lesser median coverts of underwing may be lighter brown than in Alternate plumage.

Definitive Alternate Plumage

Plumage sexually dimorphic. Distinguishing features of males: Crown and center of forehead black-brown, broadly and evenly streaked by rufous-brown feather edges. Often has prominent white spot in front of eye. Rest of supercilium rufous brown, bordered below by thin black eye-stripe, which becomes a large dark smear on central and lower ear coverts. Rest of ear coverts rufous brown. Cheeks cream with varying rufous-brown wash; sometimes uniform rich rufous brown. Chin white next to bill; rest rufous brown. Throat, nape, and neck rufous (140). Upperparts, including mantle, upper back, and scapulars black-brown, mottled or streaked by uneven rufous-brown feather fringes (which are often broken into 2 or 3 terminal spots); feathers can be narrowly tipped white. Lower back dark brown with narrow white fringes at tips of feathers. Rump and shorter uppertail coverts white, heavily barred and speckled dark brown; feathers black-brown basally, with pair of broad buff or white lateral spots (often meeting at shafts to form subterminal band), broad brown terminal bands, and narrow white fringes at tips. Longer uppertail coverts buff to white with series of inverted black-brown rosethorns (= chevrons) that become dark brown near tip; final subterminal rosethorn edged rufous brown; broad buff tip fringed with rufous brown. Underparts mostly rufous brown; when fresh, all feathers have off-white fringes and breast sometimes rufous; fringes quickly lost with wear (or replaced by Supplemental plumage [Jukema and Piersma 2000] just before and during migration); few with fringes by northward migration. Feathers of sides of breast and some feathers of belly have dark-brown subterminal bars or streaks, becoming chevrons on flanks and thigh-patch. Rear of belly, vent, and under tail vary from off white with rufous-brown wash to completely rufous brown. Tail mostly dark brown with varying patterns of barring and streaking; outer rectrix (R6) with 6–8 buff lateral spots on outer web; rectrices 2–5 spotted or barred buff; innermost rectrix (R1) with buff lateral spots reaching shaft of inner web and long cream transverse streak on outer web. Upper wing: all secondary coverts light gray-brown with dark-brown shaft streaks; lesser coverts tipped buff; outer median coverts broadly edged buff and some inner greater primary coverts and greater secondary coverts tipped white. Remiges black-brown with almost-black webs; basal fifth of inner webs mottled white. Secondaries and inner primaries retain broad white tips from Basic plumage. Fresh (breeding) tertials dark brown with black-brown shaft streaks and orange-buff terminal spots on inner webs. Humerals brown with complete white fringes broken by small terminal or subterminal spots with pink-buff or dull-pink (5) wash. Under wing: white, heavily barred brown (narrow black bars, dots, and U-marks in subspecies lapponica). Marginal- and lesser coverts white with broad brown bases. Primary- and median secondary coverts white with broad dark-brown submarginal bands and brown shaft streaks. Greater-coverts light gray (85) with narrow white fringes on greater primary coverts; outer greater secondary coverts have broad white fringes (formed by white submarginal marks) and increasing white submarginal streaks and spots on inner greater secondary coverts. Axillaries brown and barred off-white; smaller axillaries have off-white lateral or terminal spots on outer webs, and off-white transverse streak on inner web, and barring sometimes broken or angled.

Alternate female always duller than Alternate male; sexing usually possible in the field, especially combined with longer bill of females (see Measurements, below). Usually lacks all rufous tinges of adult male breeding and appears similar to adult nonbreeding, differing from both by combination of: (1) feathers of crown, mantle, scapulars, tertials, and upperwing coverts have large dark centers (like Alternate male) but with pale cinnamon (approximately color 39) to buff edges or marks; (2) tips of scapulars partly gray; (3) usually retains more gray Basic plumage on upperparts and upperwing coverts than Alternate male; especially among scapulars; (4) uppertail coverts barred dark and white, usually without cinnamon or buff tinge; (5) usually has buff to rufous-cinnamon (39–40) tinge to foreneck, breast, foreflanks, and sides of neck and throat, though in some this restricted to sides of breast and foreflanks, and in a few, ventral ground color like adult nonbreeding; (6) underparts and neck more extensively barred or streaked darker than Definitive Basic, with broad dark gray streaking on foreneck and sides of neck merging to fine barring on flanks and undertail coverts. Rarely more brightly colored like adult male: underparts, head, and neck have many rufous-brown feathers, usually lighter and more cinnamon (approximately color 240) than males but not differing in brightest birds; in general, plumage has scattered off-white feathering on underparts, especially on belly, rear flanks, and lower breast; supercilium usually off white and upperparts similar to duller adult females. Dark barring and streaking of underparts and neck less striking than duller females, but usually visible on breast and flanks (cf. breeding male).

Molts

Complex molt. Most of this section from Cramp and Simmons 1983 and Higgins and Davies 1996. First migrate south in distinctive Juvenile plumage. Delay partial first Prebasic molt to first immature plumage (= nonbreeding) until near or at nonbreeding areas. Partial Prealternate molt sometimes resulting in subdued breeding plumage among immatures which usually remain in nonbreeding areas through third austral winter. Adult (nonbreeding) appearance attained with complete second Prebasic molt about Aug–Sep of second year. Thereafter, 2 molts annually: partial Prealternate to (sexually dimorphic) breeding plumage just before and during northern migration, and complete Prebasic molt to nonbreeding plumage just before and after southern migration. Recent evidence that Prealternate molt in L. lapponica of e. Atlantic flyway produces 2 consecutive plumages, including “striped” (Alternate) plumage of late winter-early spring and Supplemental, or breeding plumage, carried to breeding grounds (Piersma et al. 1993b, Jukema and Piersma 2000). Following descriptions for baueri subspecies. Colors referenced according to Smithe 1975. See Figure 3 for summary of molt timing.

Juvenile Plumage

Prejuvenile molt progresses rapidly, fledging in ≤30 d (see Breeding: young birds, above).

Basic I Plumage

First Prebasic (Postjuvenile) molt partial, occurring mid-Sep–Feb; involves head, neck, mantle, scapulars, outer upperwing coverts, some uppertail coverts and shorter tertials. In mid-Jun, 63% of 1-yr-old females in se. Australia (n = 19) had undergone complete primary molt, while same in only 36% of males (n = 28). Additional 11% of females and 21% of males with partial, arrested primary molt and 25% of each sex with no remigial molt (Barter 1989a; missing value for males not explained).

Alternate I Plumage

First Prealternate molt partial, occurring Apr–May. Described as Presupplemental molt occurring after Basic I plumage (Higgins and Davies 1996) but possibly interrupted or delayed part of Prebasic molt; poorly understood and only known for Australia, where many birds replace some or all primaries from late Mar to early Apr (Barter 1989a). Some may complete full Prealternate molt and appear like adults, but most (90%) attain only partial adult plumage, usually being <25% of full Alternate plumage; none migrates to breed (Barter Barter 1989a, Barter and Wang 1990).

Definitive Basic Plumage

Third and subsequent Prebasic molts Definitive; complete molt, occurring Jul–Feb. Body molt may begin on Alaska breeding grounds, but quite obvious on staging grounds in Sep–Oct; onset may be earlier in males than females (REG, BJM; needs study). Flight feathers retained until on nonbreeding grounds and then molted outward (late Aug–early Feb); timing and duration varies by region, averaging 120 d (Barter 1989a), but 104 d in nominate race in Netherlands (Boere 1976). In baueri, no differences between sexes in duration of remigial molt and no evidence of such molt after 1 Mar.

Definitive Alternate Plumage

Attained from second and subsequent Prealternate molts; first attained at end of second austral summer, late Feb–May. Begins immediately after completion of Prebasic molt or possibly overlaps. In nominate lapponica, molt involves 2 feather generations, striped and breeding (Piersma et al. 1993b, Jukema and Piersma 2000). For baueri, begins on nonbreeding areas and completed (especially females) on e. Asian staging grounds. Sexes differ in timing and extent of molt, with males earlier; males in se. Australia in advanced body molt in late Mar–early Apr. Molt even earlier in New Zealand, where 10% of birds in mid-Jan attaining reddish plumage (P. Battley in Higgins and Davies 1996).

Bare Parts

Bill And Gape

From Higgins and Davies 1996 . Bill bicolored; basal 30–50% of adult bill dull pink (5) to pink-red (approximately color 108C); often with dark-gray to gray-black lines along dorsal culmen from base to tip, with distal 50–70% entirely gray-black (Thurston 1996). In breeding season, pale base of adult bill more extensive (basal 50–60%). In breeding males only, base of bill brightens to orange (approximately color 17) during early nesting period only. Base of juvenile bill dull salmon (6). Bill of hatchling bluish gray (Baicich and Harrison 1997).

Iris

Black-brown or dark brown (20 or 119) in adult and juvenile (Higgins and Davies 1996); blue in hatchling (Cramp and Simmons 1983).

Legs And Feet

Tarsus slender, scutellate. Minute, narrow webs along sides of toes and between front toes. Claws black. Middle claw short, curved; not specialized as in Black-tailed Godwit (Cramp and Simmons 1983). Color variable; usually greenish gray (Cramp and Simmons 1983), but occasionally black to gray black (82) to black-brown, or, exceptionally, dark olive-brown (129; Higgins and Davies 1996). Legs and feet of hatchlings bluish gray (Baicich and Harrison 1997).

Measurements

Linear Measurements

See Appendix 1 . Females of all subspecies average significantly larger than males in all measurements (Cramp and Simmons 1983, Higgins and Davies 1996, Engelmoer and Roselaar 1998).

Mass

See Appendix 2 . Highly variable with season, usually doubling twice annually in preparation for migration; females average significantly heavier than males in all months (Higgins and Davies 1996). Information generally lacking for breeding birds. Mass data for other subspecies presented in Boere and Smit 1981, Cramp and Simmons 1983, Piersma et al. 1990b, Higgins and Davies 1996 .

Bar-tailed Godwit Adult male Bar-tailed Godwit, breeding plumage
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Adult male Bar-tailed Godwit, breeding plumage

; photographer Brian E. Small

Bar-tailed Godwit Adult female Bar-tailed Godwit; Alaska, June
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Adult female Bar-tailed Godwit; Alaska, June

Colville River Delta, Alaska, June.; photographer Gerrit Vyn

Bar-tailed Godwit Adult female Bar-tailed Godwit, incubating; Alaska, June
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Adult female Bar-tailed Godwit, incubating; Alaska, June

Colville River Delta, Alaska, June.; photographer Gerrit Vyn

Bar-tailed Godwit Figure 3. Annual cycle -- Bar-tailed Godwit.
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Figure 3. Annual cycle -- Bar-tailed Godwit.

Annual cycle of migration, breeding, and molt of Bar-tailed Godwit (L. l. baueri). Thick lines show peak activity; thin lines, off-peak. Spring migration data from entire route, Australia to Alaska; fall migration shows Alaskan data only, including postbreeding movements to the staging grounds and departures to Australasia. Molt complex; only breeding-age birds depicted here (see text for details). Breeding data from Yukon-Kuskokwim Delta, AK.

Recommended Citation

McCaffery, B. J. and R. E. Gill (2020). Bar-tailed Godwit (Limosa lapponica), version 1.0. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.batgod.01