Appearance

White-throated Sparrows have 9 functional primaries, 9 secondaries (including three tertials), and 12 rectrices. Wings are moderately rounded and tail is squared and moderately long. No geographic variation in molt strategies or appearance described, but adults in definitive plumages are polymorphic in plumage color, both males and females showing white-striped or tan-striped crowns (see Behavior: sexual [polymorphism and assortative mating], and below). Because variation in plumage color in White-throated Sparrows was not recognized as polymorphic until 1961, previous accounts of the sequence of molts and plumages assumed that differences in plumage color were correlated with age and/or sex and, therefore, reported erroneous sequences of plumages or correlations of plumages with age and/or sex (e.g., Stone 1896, Dwight 1900).

Molts

Molt and plumage terminology follows Humphrey and Parkes (1959) as modified by Howell et al. (2003, 2004). White-throated Sparrow exhibits a Complex Alternate Strategy (cf. Howell et al. 2003), including complete prebasic molts, a partial preformative molt, and limited prealternate molts in both first and definitive cycles (Stone 1896; Dwight 1900; Lowther and Falls 1968; Oberholser 1974; Cramp and Perrins 1994; Pyle 1997a, 1997b; Fig. 5). Definitive molt cycle commences with Second Prebasic Molt.

Prejuvenal (First Prebasic) Molt

Complete, May-Jul, in the nest. See Breeding: young birds for details.

Preformative Molt

"First prebasic molt" of Pyle (1997a) and previous authors. Partial, Jul-Sep, on or near breeding grounds. Usually includes all body plumage and all lesser, median, and greater secondary coverts but no tertials or other wing or tail feathers.

First And Definitive Prealternate Molts

Limited, late Feb-May, on or near winter grounds, although may occasionally complete on northbound migration or breeding grounds. Restricted primarily to feathers of head, but occasionally may include 1-2 inner tertials and/or 1-2 central rectrices. Does not occur Oct–Apr as stated by Forbush (1929), and is not absent as stated by Stone (1896). Molt begins earlier and lasts longer in tan-striped males than in tan-striped females; these differences are slight but statistically significant. Otherwise timing of molt does not differ between plumage morphs and sexes (Kuenzel and Helms 1974).

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. Timing of molt does not differ between plumage morphs or sexes (Kuenzel and Helms 1974, Lowther and Falls 1968).

Plumages

Following based primarily on plumage descriptions of Chapman (1876), Brewster (1878), Dwight (1900), Ridgway (1901), Graber (1955), Roberts (1955), Lowther and Falls (1968), Oberholser (1974), Cramp and Perrins (1994), Byers et al. (1995), and Rising (1996); see Pyle (1997a) for age-related criteria. The expression of morph type is genetically determined (Thorneycroft 1966, 1976), but is unequally distributed among plumage and sex classes (Vardy 1971, Atkinson and Ralph 1980, Piper and Wiley 1989). Methods for identifying morph types in Alternate and Basic plumages are reviewed by Watt (1986b), Piper and Wiley (1989a), and Micholopoulos et al. (2007). Definitive plumage aspect is essentially assumed following Second Prebasic Molt.

Sexes show similar aspects in all plumages but males appear to average slightly brighter and less streaked head plumage than females when accounting for age and morph type (Graber 1955, Pyle 1997a). Sexing by wing length reviewed by Piper and Wiley (1991) and Pyle (1997a); see Schlinger and Alder (1990) for sexing of specimens using multiple logistic regression on wing length and head plumage. In the breeding season (May-Aug), birds can be sexed by cloacal protuberance (Wolfson 1952, Pyle 1997a); DNA analysis provides a means of accurately determining sex and morph (Micholopoulos et al. 2007). Also see Measurements.

Natal Down

Present Apr-Jun. Chicks altricial; pale clove brown down on coronal, occipital, mid-dorsal, pelvic (upper) scapular, femoral, crural, rectrix, and greater and median secondary covert tracts (Dwight 1900, Wetherbee 1957). For specific counts and lengths of neossoptiles in each feather tract see Wetherbee (1957).

Juvenal (First Basic) Plumage

Present late Jun-early Aug. Feathers above nostrils whitish. Forehead, crown, and nape chestnut brown streaked obscurely with black. Distinct median crown stripe buffy white. Back chestnut, streaked profusely with black, some feathers edged with buff. Rump and upper tail coverts brown or rusty brown, obscurely streaked with black. Flight feathers deep olive brown to blackish medially; edged whitish on primaries, chestnut on secondaries (including tertials which also are tipped with buff), and rusty (broadly) on rectrices. Coverts black centrally, edged with rust on greaters and lessers; median and greaters also tipped white or buffy white. Edge of wing white. Lores gray or dusky. Superciliary line white or buffy white to olive gray buff tinged, extending to nape. Eye-ring white, interrupting dusky eye stripe. Auriculars gray, mottled dusky. Postauriculars streaked brown or buffy. Chin and throat whitish, flecked with dusky and with blackish mustachial marks. Chest, sides, and flanks tinged buffy, heavily streaked with black; belly and crissum white, both largely unmarked.

Formative Plumage

Present late Aug-Mar. Lateral crown stripe black anteriorly grading to mixture of black and brown on neck. Median stripe olive gray or lighter tan; a few birds (11 out of 209 museum specimens) have median stripe white. Eyebrow stripe yellow in front of eye and light tan posteriorly. Edge of wing pale yellow. Throat patch white or dull white edged with black and with 2 black malar lines through throat patch extending posteriorly from lower edge of each side of lower mandible. Breast ash gray with brown vermiculations, a central spot in some individuals. Breast streaks of variable strength present in most individuals, not retention of juvenile plumage (Parkes 1993). Abdomen white, flanks washed with brown and dusky streaks. Back chestnut brown streaked with dull black, feathers edged with beige. Wing feathers olive brown edged with buff. Median and greater coverts tipped with white, forming 2 narrow wing-bars. Rump gray brown with faint streaks.

Individuals in Formative Plumage average duller than those in Definitive Basic Plumage (especially white-striped individuals); best aged by paler brown and abraded retained juvenal primary coverts, contrasting with fresher replaced formative greater coverts, and narrower, more abraded, and more tapered outer primaries and outer rectrices (Pyle 1997a).

First And Definitive Alternate Plumages

Present Mar-Aug. Two color morphs obvious in Definitive Alternate plumage (see Behavior: polymorphism and assortative mating). Plumage patterns of both morphs similar to those of birds in Formative Plumage; color intensities of certain parts of body vary by morph, independent of sex. White-striped birds generally brighter colored and less streaked; median stripe white; more black on lateral crown stripes; less streaking on wider, grayer chest band; ear coverts and cheek gray; malar stripes less intense; eyebrow stripe brighter yellow. Tan-striped birds similar to most birds in Formative Plumage. Ageing criteria outlined under Formative Plumage applies to separation of First from Definitive Alternate plumages.

Definitive Basic Plumage

Present Sep-Feb. Differs little from Alternate Plumage except in head pattern. Some White-striped individuals retain bright crown coloration; most have median crown stripe and posterior eyebrow stripe tinged with buff. Tan-striped birds show no apparent change in plumages. See Formative Plumage for ageing criteria.

Aberrant Plumage Coloration.

Chapman (1876) reported leucistic plumages as did Evans (1995), Brooks et al. (1998), and Brent Horton (pers. comm.). Longly (1990) described an individual with a white head (“hood”) from Minnesota. Five leucistic specimens were located in collections by Ross (1963) who also found 6 other records. A number of birds with orange lores have been reported (Bilsborough 1987, Brooks 1994, Craves 1999, Derbyshire and Flinn 2007). Brooks suggested that changes in feather pigments resulted from birds feeding on Morrow’s or Tartarian Honeysuckle (Lonicera morrowi and L. tartarica) berries in fall as occurs in Cedar Waxwings (Bombycilla cedrorum). She also quotes Kenneth Parkes who found two xanthochroistic White-throated Sparrows in the collection of the Carnegie Museum of Natural History. One bird from New York had yellow underparts and throat and a dirty yellow superciliary line while the other from James Bay had orange-buff on its throat, belly and under-tail coverts.

Bare Parts

Bill And Gape

Bill slaty brown in immatures becoming dark brown above, bluish gray below in adults. Gape bright yellow becoming pale cream yellow or darker pale flesh gray (Yunick 1977).

Iris

Gray-brown in immatures (until skull ossification complete in late winter or early spring), reddish brown in adults (Yunick 1977, Pyle 1997a).

Legs And Feet

Pale pink or pale brown.