SPECIES

Blackpoll Warbler Setophaga striata Scientific name definitions

William DeLuca, Rebecca Holberton, Pamela D. Hunt, and Bonita C. Eliason
Version: 1.0 — Published March 4, 2020
Text last updated June 4, 2013

Plumages, Molts, and Structure

Plumages

Blackpoll Warblers have 9 functional primaries, 9 secondaries (including 3 tertials), and 12 rectrices. Proportionally long wings (longest tertial tip to longest primary tip 20-26 mm; p9 > p8 by 0-2 mm and p8 > p7 by 2-3 mm), p6 not emarginated, and longer distance between undertail coverts and tail (12-15 mm) are structural differences compared to similar Setophaga warblers; e.g., Bay-breasted Warbler S. castanea and Pine Warbler S. pinus (Stiles and Campos 1983). Little or no geographic variation in appearance (see Systematics: Geographic Variation) or geographic or sex-specific variation in molt strategies reported.

Following based primarily on detailed plumage descriptions of Dwight (1900), Ridgway (1902), Bent (Bent 1953b), Roberts (1955), Oberholser (1974), Cramp and Perrins (Cramp and Perrins 1994b), Curson et al. (Curson et al. 1994), and Dunn and Garrett (Dunn and Garrett 1997); see Robbins (1964) and Pyle (1997a) for specific age-and sex-related criteria. Appearances of sexes similar in Juvenile and Formative Plumages, show slight average differences in Basic Plumages, and show substantial differences in Alternate Plumages. Definitive Plumages essentially assumed at Second Basic and Second Alternate Plumages.

Natal Down

Present primarily Jun-Jul, in the nest. Grayish down on capital, scapulo-humeral, crural, alar, and caudal tracts (Bent 1953b).

Juvenile (First Basic) Plumage

Present Jun–Aug, on and near natal territory. Plumage ephemeral and variation not well described. Upperparts mottled olive gray and streaked with black; lores blackish; auriculars buffy gray; upperwing secondary coverts brownish black, edged with olive green and with pale buff-yellow tips to median and greater coverts, filamentous in structure; underparts grayish white, mottled with blackish brown, sometimes tinged with yellow; remiges and rectrices dark brownish black, the outer two rectrices (r5-r6) with white patches. Juvenile males average slightly more white to outer rectrices (especially r5) than juvenile females; otherwise sexes similar.

Formative Plumage

"First Basic" or "Basic I" plumage of Humphrey and Parkes (1959) and later authors; see revision by Howell et al. (2003). Present primarily Sep–Mar. Similar to Definitive Basic plumage of female but body plumage averages yellower; back feathers and uppertail coverts with smaller and less-distinct blackish centers; rump feathers and uppertail coverts with duller and greener (less gray) edging; throat without blackish spotting; streaks to flanks duskier and less distinct. Formative males average slightly brighter, with larger and more distinct blackish centers to upperpart feathers and more-extensive white patches to outer rectrices than Formative females, but most or all individuals not reliably sexed by plumage.

In both sexes Formative Plumage most reliably distinguished from Definitive Basic Plumage by molt limits and characters among upperwing and tail feathers: 1-3 tertials sometimes replaced, contrasting with older retained juvenile tertials and secondaries; primary coverts duller, with little to no olive edging, browner, and more worn, contrasting markedly with newer and blacker formative greater coverts; retained juvenile outer primaries and rectrices thinner, more pointed, browner, and relatively more worn; outer rectrices average less white, with little or none on r4 (Pyle 1997a).

First And Definitive Alternate Plumages

Present primarily Mar–Aug. Sexes differ substantially in plumage. Male. Crown and top of head down to middle of eye and upper nape black; lower nape, rear sides of neck, and remainder of upperparts olive gray, with broad black feather centers producing heavy coarse streaking or mottling, somewhat less boldly on rump and uppertail coverts. Remainder of head and all underparts white, with bold black streaking from bill through malar area, extending onto sides of neck and down along the sides and flanks; auriculars sometimes with small black marks. Rectrices, primaries, secondaries, and primary coverts retained and as in Definitive Basic Plumage; 1-3 tertials replaced alternate, blacker than remaining secondaries and with bold white outer edges; some to all upperwing median and greater coverts replaced alternate, the coverts broadly tipped (more so on outer web) with white, forming 2 bold wing bars; remaining upperwing coverts narrowly margined with grayish olive. Underwing coverts mixed pale gray and white. Rimmer and Tietz (2001) report aberrant Definitive Alternate male showing duller, female-like plumage (see below).

Female. Plumage variable, with some individuals approaching Definitive Alternate male but duller and less-boldly patterned. In brighter individuals plumage differs from male in having crown olive gray, heavily marked with narrow black streaks, creating vaguer appearance of black cap than in male; remaining upperparts with narrower black feather centers, producing less bold streaking throughout; remaining portions of head and entire underparts duller white, with less extensive and much narrower black streaking; white tips on replaced alternate median and greater upperwing coverts often interrupted by black shaft-line. These individuals show grayish upperparts with only slight olive wash, and little or no buffy or yellowish color on the underparts. Duller alternate females similar except streaking on upperparts even narrower, streaking on head sometimes reduced to small rows of spots or largely absent, dull whitish supercilium and gray transocular line barely extending to or beyond eye, and ventral streaking narrower and reduced in extent (some with bolder streaking). These individuals can show extensive olive wash to upperparts and underparts with pale buffy to yellow wash, particularly along sides of throat, sides, and flanks. In yellowest individuals the upperparts can be bright olive green and the greater coverts can be margined on the outer web with grayish olive. Amount of white to outer rectrices averages smaller in females than in males, age for age (see Formative and Definitive Basic Plumages).

Criteria to separate first Alternate from Definitive Alternate plumages, in both sexes, similar to that described under Formative and Definitive Basic plumages, with molt contrasts in wing and differences in condition of outer primaries and rectrices more pronounced, due to accelerated rates of wear to juvenile feathers as compared with formative feathers. First Alternate males also average less-extensive black streaking on malar area than shown by Definitive Alternate males; First Alternate females average sparser dorsal and ventral streaking than in Definitive Alternate females.

Definitive Basic Plumage

Present primarily Sep–Mar. Sexes show average differences in plumage. Male. Upperparts dull olive, the feathers with concealed black centers, narrower on top of head and lower rump, more rounded and distinct on back, scapulars, and upper rump; uppertail coverts olive-gray with dark central streak. Remainder of head dull olive, becoming palest on chin and throat, and with short dusky transocular line, pale supercilium, and narrow pale eye crescents; some with black spots in malar region. Remaining underparts white, tinged with yellow, becoming olive on sides and flanks, and with dark grayish streaking on breast, sides, and flanks; undertail coverts brighter white and unstreaked. Wing feathers blackish; tertials broadly edged on outer web with dull white; primaries and secondaries edged on outer web with olive and primaries tipped primarily on outer web with dull white when fresh; upperwing median and greater coverts broadly tipped (mostly on outer web) with dull white, forming two wing bars, and margined basally on outer web with olive; primary coverts narrowly edged on outer web with olive. Rectrices blackish, margined with grayish olive, the outermost 2 rectrices (r5-r6) with large white patches at distal half of exposed portion of inner webs (spot does not quite reach tip of feather) and r4 sometimes or often with small white spot.

Female. Similar to Definitive Basic male but duller and greener overall, blackish centers to upperpart feathers smaller and less distinct, underparts duller white and often with yellowish tinge, white patches to outer rectrices average smaller, r4 only occasionally with small white spot.

In both sexes Definitive Basic Plumage separated from Formative Plumage by having wing and tail feathers uniform in quality and freshness: tertials and inner secondaries uniform in wear; primary coverts duskier, averaging wider olive edging, not contrasting in feather quality with greater coverts; basic outer primaries and rectrices broader, more truncate, duskier, and relatively fresher; amount of white to rectrices (especially r4-r5) greater by sex (Pyle 1997a).

Aberrant Plumages

Bent (Bent 1953b) reports several instances of albinistic or leucistic individuals.

Molts

General

Molt and plumage terminology follows Humphrey and Parkes (1959) as modified by Howell et al. (2003, 2004). Blackpoll Warbler exhibits a Complex Alternate Strategy (cf. Howell et al. 2003, Howell 2010), including complete prebasic molts, a partial preformative molt, and limited-to-partial prealternate molts in both first and definitive cycles (Stone 1896; Dwight 1900; Bent 1953b; Oberholser 1974; Cramp and Perrins 1994b; Curson et al. 1994; Dunn and Garrett 1997; Pyle 1997a, 1997b; Fig. 4). Relatively extensive prealternate molt may have evolved first in this highly migratory species to combat effects of increased insolation (from switching Hemispheres during migration and experiencing two summer periods), followed by acquisition of bright male plumage by sexual-selection purposes, as proposed for other Setophaga warblers (Pyle and Kayhart 2011).

Prejuvenile (First Prebasic) Molt

Complete, Jun–Jul, in the nest. Pin-feathers showing on wings 3 d after hatching, body feathers begin to erupt from feather sheaths by 6–7 d, and remiges erupt from sheaths in 7–8 d (Bent 1953b). Presumably completed or near-completed before fledging at d 9-10.

Preformative Molt

"First Prebasic" or "Prebasic I" Molt of Humphrey and Parkes (1959) and some later authors; see revision by Howell et al. (2003). Partial, Jun–Aug (Fig. 4), often commencing in nest and completing shortly after fledging, on breeding grounds. Includes most or all body feathers and upperwing secondary coverts, and sometimes the greater alula and/or 1-3 tertials, but no other secondaries, primaries, primary coverts, or rectrices.

First And Definitive Prealternate Molts

Partial, primarily Mar-Apr (Fig. 4), on or near non-breeding grounds. Includes most or all body feathers, some to most upperwing lesser and median coverts, 5-10 medial greater coverts, and 1-3 tertials, but no other secondaries, primaries, primary coverts, or rectrices. First Prealternate Molt likely averages later and less extensive than Definitive Prealternate Molt but these molts otherwise similar in timing, sequence, and extent. Reports that Prealternate Molts can begin as early as Oct on non-breeding grounds (Pyle 1997a) require confirmation; limited body-feather replacement at this time may be instead part of protracted/suspended Preformative and Prebasic Molts.

Definitive Prebasic Molt

Complete, Jul–Aug (Fig. 4), on or near breeding grounds, although study needed on the relationship between breeding territories and molting grounds. Primaries replaced distally (p1 to p9), secondaries likely replaced proximally from s1 and proximally and distally from the central or innermost tertial (s8 or s9), as typical of passerines, and rectrices probably replaced distally (r1 to r6) on each side of tail, with some variation in sequence possible. Replacement of body feathers reported to commence before start of flight-feather molt (Bent 1953b); confirmation needed as most passerines commence Prebasic Molt with dropping of first primary (Pyle 1997a).

Bare Parts

Bill And Gape

Pinkish in juvenile. In adult, upper mandible and tip of lower mandible blackish. Remainder of lower mandible dusky pink, may become pale yellow or dark gray in autumn (Curson et al. 1994, Dunn and Garrett 1997).

Iris

Sepia brown, dark brown, or black (Curson et al. 1994, Dunn and Garrett 1997).

Legs And Feet

Legs pale orange-yellow, darker on sides in female and paler in juvenile. Legs may be dark in fall immatures (Basic I plumage). Soles of feet orange-yellow in all ages (Curson et al. 1994, Dunn and Garrett 1997).

Measurements

Linear Measurements

Mean measurements (and range, in mm) of male (n = 25) and female (n = 17; from Ridgway 1902). Bill length (exposed culmen): male 9.9 (no range given), female 10.0 (9-11). Wing length: male 74.2 (71.4-77.6), female 71.5 (69-75). Tail length: male 51.3 (48.6-54.0), female 48.4 (45-51). Tarsus length: male 19.1 (18.4-20.4), female 19.1 (18.0-20.0). Differences between sexes significant for bill, wing, and tail (based on different set of measurements; Cramp and Perrins 1994b). Wing and tail measurements of individuals from Alaska and n. Rocky Mtns. average slightly larger than those in eastern portions of range (Ridgway 1902). From Mount Jefferson, NH mean measurements (and range, in mm) of male (n = 37) and female (n = 7; WVD). Bill length (anterior edge of nostrils to tip): male 7.7 (7.0-8.9), female 7.6 (7.4-8.3). Bill width (at anterior edge of nostrils): male 3.2 (2.8-3.8), female 3.3 (2.8-3.8). Bill depth (anterior edge of nostrils): male 3.2 (2.8-3.6), female 3.2 (3.0-3.4). Wing length: male 72.6 (68.0-76.0), female 68.9 (66.5-71). Tail length: male 50.0 (45-53), female 49.0 (47.0-50.0). Tarsus length: male18.6 (17.2-20.1), female 18.5 (17.4-19.6).

From the Green Mountains, VT mean measurements (and range, in mm and sample size; K. McFarland unpublished data). Bill length (exposed culmen): male 10.1 (8.3-14.6, 191), female 10.0 (8.7-11.2, 114). Bill width (at anterior edge of nostrils): male 3.4 (2.9-4.8, 186), female 3.4 (2.7-4.8, 113). Bill depth (anterior edge of nostrils): male 3.4 (2.2-4.0, 185), female 3.3 (2.1-3.7, 112). Wing length: male 72.2 (63.5-81.0, 636), female 68.9 (60.0-78.0, 455). Tail length: male 49.5 (40-59, 316), female 47.9 (41.0-59.0, 229). Tarsus length: male18.6 (17.2-20.1), female 18.5 (17.4-19.6).

Mass

Fat-free mass of 10.34 g ± 0.78 SD (range 8.82-11.84, n = 19, Dunning 1993b). Means of birds on breeding grounds in NB (range in parentheses): males 11.9 g (10.6-12.8, n = 17), females 12.7 g (11.2-14.7, n = 17, BCE) , on Mount Jefferson (WVD): males 11.8g (10.6-13, n = 37), females 11.9 g (11.0-12.9, n = 7), and in the Green Mountains, VT (K. McFarland unpublished data): males 11.9g (7.8-21.1, n = 587), females 12.1g (9.2-17.4). In the Green Mountains data, individuals with high were caught in July while molting and in near darkness before roosting for the night (K. McFarland unpublished data).

Individuals can almost double breeding mass before long migratory flights in fall, although average mass is only slightly higher than breeding season. Mean fall masses include 11.2-16.4 g in e. Massachusetts (range of means over several age/sex/fat classes, overall range 9.3-21.5, overall n = 1,816; Nisbet et al. 1963); 11.5 g (8.8-21.9, n = 609, Murray 1979) and 12.9 g (8.5-22.1, n = 143; Murray and Jehl 1964) in coastal New Jersey; 13.7-16.64 g in Bermuda (n = 141; Nisbet et al. 1963); 10.8 g in Puerto Rico (9.1-12.6, n = 60; M. Baltz pers. comm.). Adults averaged slightly higher mass than yearlings within a sex (Nisbet et al. 1963). See also Migration, above.

Blackpoll Warbler Breeding adult male Blackpoll Warbler, Petty Harbor, NL, 29 May.
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Breeding adult male Blackpoll Warbler, Petty Harbor, NL, 29 May.

Adult male Blackpoll Warbler in breeding plumage is difficult to confuse with any other North American bird. Black-and-white Warbler and Black-throated Gray Warbler are superficially similar, but neither has the combination of field marks shown by male Blackpoll. The following is a link to this photographer's website: http://www.flickr.com/photos/oceanites/.

Blackpoll Warbler Breeding adult male Blackpoll Warbler, Seward Peninsula, AK, June.
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Breeding adult male Blackpoll Warbler, Seward Peninsula, AK, June.

Note white cheek contrasting with solid black cap and black malar stripe.; photographer Gerrit Vyn

Blackpoll Warbler Breeding male Blackpoll Warbler, Churchill, MB, 19 June.
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Breeding male Blackpoll Warbler, Churchill, MB, 19 June.

Note this bird's rather faded brownish flight feathers and primary coverts, likely indicating that it is a first-spring male. The following is a link to this photographer's website: http://www.flickr.com/photos/glennbartley/.

Blackpoll Warbler Female Blackpoll Warbler, Chambers Co., TX, April.
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Female Blackpoll Warbler, Chambers Co., TX, April.

Breeding female Blackpolls are variable, though most are similar to this bird. Note the streaked underparts and back, pale yellowish legs, and bold white wing bars.; photographer Brian E. Small

Blackpoll Warbler Basic plumage Blackpoll Warbler, off the Maine coast, 5 October.
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Basic plumage Blackpoll Warbler, off the Maine coast, 5 October.

It is difficult to age and sex Blackpoll Warblers with certainty in fall in the field. Fall adult males generally show more streaking below and a dark lateral throat stripe. This bird is aged as an adult based on its broad truncate primary coverts, and is thus likely an adult female. This bird landed on a ship off the coast of Maine during migration. The following is a link to this photographer's website: http://www.flickr.com/photos/bonxie88/.

Blackpoll Warbler First-fall Blackpoll Warbler, Chester Co., PA, 4 November.
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First-fall Blackpoll Warbler, Chester Co., PA, 4 November.

Fall Blackpolls are often confused with Bay-breasted Warblers. While the two are strikingly different in breeding plumage, in basic plumage they are very similar. Blackpolls usually show blurry streaks on the breast sides, have white undertail coverts, and have yellow soles to the feet, which often extend to some page on the rear portion of the legs. Bay-breasted usually shows some hint of bay or buff on the flanks, has yellowish undertail coverts, and dark legs. The following is a link to this photographer's website: http://www.flickr.com/photos/puttefin/.

Recommended Citation

DeLuca, W., R. Holberton, P. D. Hunt, and B. C. Eliason (2020). Blackpoll Warbler (Setophaga striata), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.bkpwar.01