Appearance

Figure 5. Annual cycle of breeding and molt in the White-breasted Nuthatch

White-breasted Nuthatches have 10 functional primaries (the outermost reduced in length), 9 secondaries (including three tertials), and 12 rectrices. The following plumage descriptions pertain to the nominate subspecies (S. c. carolinensis) of northeastern North America; see Systematics: geographic variation for variation between carolinensis and populations in southeastern and western North America and Mexico. No geographic variation in molt strategies reported.

Molts -- by P. Pyle, 5/08

Molt and plumage terminology follows Humphrey and Parkes (1959) as modified by Howell et al. (2003, 2004). White-breasted Nuthatch appears to exhibit a Complex Basic Strategy (Howell et al. 2003), including a partial preformative molt in the first cycle but no prealternate molts (Fig.5). See below regarding reported existence of prealternate molts.

Prejuvenile (First Prebasic) Molt

Complete, May-Jul, in the nest (Dwight 1900). No information on timing or sequence.

Preformative Molt Partial

Jul-Sep, on or near the breeding grounds. Includes most to all body feathers and a few to some lesser coverts, but no median or greater coverts, primaries, primary coverts, secondaries, or rectrices (Dwight 1900, Bent 1948, Roberts 1955, Pyle 1997a, 1997b). Harrap and Quinn (1995) reported that a variable number of greater coverts could be replaced but Pyle (1997b) found no evidence of this.

First And Definitive Prealternate Molts

Absent (Stone 1896, Dwight 1900, Bent 1948, Oberholser 1974, Pyle 1997a). Occasionally reported as limited in some birds (Roberts 1955, Banks 1978), as in other nuthatches, but detailed studies need to confirm this.

Definitive Prebasic Molt

Complete, Jun-Sep, on or near the breeding grounds. No information on sequence but presumably the same as in other nuthatches and birds.

Plumages

See also Ridgway (1904) and Oberholser (1974) for detailed plumage descriptions. Sexes differ in all plumages, including juvenal plumage.

Natal Down

No information.

Juvenal Plumage

(Jun-Aug) similar to definitive basic plumage (see below), but crown plumage paler and duller by sex and plumage loosely textured (Pyle 1997a). Back feathers may have dark tips and scapulars paler tips creating barred appearance; outer secondaries may be fringed orange-buff at base; underparts duller and all but chin washed buff (Harrap and Quinn 1995). Compared to definitive basic plumage (below), female averages duller underparts and shows head markings duller, grayer, and less well defined by subspecies (see Systematics: geographic variation) and male shows duller, less glossy, and less sharply defined black cap (Wood 1969, Harrap and Quinn 1995, Pyle 1997a).

Formative Plumage

(Sep-following Aug) similar to definitive basic plumage (see below) of each sex, but averages duller, especially in crown plumage. Upperparts may average more ashy-gray, rather than blue-gray; central pair of rectrices and the edgings of primaries are ashen; underparts may average more grayish-white, usually faintly tinged with pinkish; the white of the sides of the head can be obscured by dusky tips (Bent 1948, Roberts 1955). Individuals in formative plumage can be aged by molt limits between fresher and darker gray back/scapulars (and a few to some lesser coverts) and more worn and browner coloration to remainder of upper wing feathers and wing-feather edging (Pyle 1997a). In formative plumage, crown color averages more grayish (less blackish) in females by subspecies and duller black in males than in definitive basic plumage (Roberts 1955, Pyle 1997a). Beware of natural color contrast (pseudolimit) among tertials that may be mistaken for a molt limit (Pyle 1997a, 1997b).

Definitive Basic Plumage

(Sep-following Aug). Back, rump, uppertail coverts, and central pair of rectrices bluish-gray, with faint suggestion of barring on latter and shafts black; sides of head (except short dark streaks back of eye) and underparts white or grayish-white, the flanks and undertail coverts rusty or cinnamon; primaries dark brownish-slate, the longest with a white spot near middle on outer web and narrow white fringe at tips; secondaries brownish-slate, margined with bluish-gray and tipped with white; tertials dark gray, margined with bluish-gray and tipped with white; wing coverts dark centrally, margined with bluish-gray, the greater ones tipped with white, forming wing-bar; under wing coverts black with large white patch formed by white bases of primaries; rectrices, except middle pair, black with large white patches near ends, outer webs of outermost rectrices are white (Roberts 1955, Harrap and Quinn 1995).

Sexes differ in plumage, primarily that of head. Female shows crown more or less obscured by bluish-gray and hindneck is black as in males. Dimorphism of crown plumage varies geographically (see Systematics: geographic variation), being less pronounced in southeastern populations, where crowns of definitive-plumaged females can be more-or-less black, matching formative-plumaged males but typically duller (less glossy) than those of definitive-plumaged males (Shepard and Klimkiewicz 1976, Wood 1992, Pyle 1997a). Females also show duller body plumage overall (Harrap and Quinn 1995, Pyle 1997a), especially upperparts (duller gray) and wing edging (dull and with brownish tinge). Males of all populations show crown and nape black glossy greenish black, and brighter body plumage overall, including upperparts (brighter bluish gray) and wing edging bluish gray without brownish tinge (Harrap and Quinn 1995, Pyle 1997a).

Individuals in definitive plumage separated from those in formative plumage by lack of molt limits between the back and wing feathers (1997a). Crown color likely also varies by sex, showing more blackish in females by subspecies and being glossier black in males.

Bare Parts

Bill And Gape

Dusky pinkish-buff in recently-fledged birds, becoming dark bluish-slate to blackish above and lighter at base below during first year, the cutting edge to mandibles off-white (Harrap and Quinn 1995, Roberts 1955).

Iris

Dark brown.

Legs And Feet

Dusky pinkish-buff in recently-fledged birds, becoming dusky-brownish with slaty cast during first year, the claws black (Harrap and Quinn 1995, Roberts 1955).