Breeding adult
The breeding plumage is acquired in the spring (March-May), usually during spring migration, and is retained until fall (September-October); thus, spring migrants and very early fall migrants can be observed in this plumage in B.C. The feathers of the back and scapulars of breeding-plumaged birds are black with variable (usually relatively broad) reddish to cinnamon-rufous or rufous-buff feather edges, giving the upperparts a mottled appearance. The rump and uppertail coverts are dark blackish-grey. The short-pointed tail is grey with black central feathers. The upperwing coverts are primarily grey or brownish-grey, with blackish-grey primary coverts. The flight feathers are also blackish-grey with a bold white stripe extending across the bases of the secondaries and inner primaries (primaries also with extensive whitish shafts). The underparts are usually largely whitish, with variable dark blackish-brown mottling on the upper breast forming an irregular dark patch; the belly, flanks, and undertail coverts are variably (usually finely) streaked with dusky-grey. The underwing coverts are largely white except for blackish-grey spotting along the front edge of the wing; the underside of the flight feathers is dark grey with a white stripe along the base of the secondaries and primaries. The crown, nape, hindneck, and sides of the neck are cinnamon-rufous or buffy with fine black streaks (heaviest on the crown), with a grey tinge to the hindneck. The relatively broad whitish supercilium contrasts with the dusky-brown lores and dark spot on the rear portion of the ear coverts; the remainder of the ear coverts are buffy and finely streaked with black. The remainder of the head and throat are whitish, often with fine dusky streaks (heaviest in C.p.couesi and relatively sparse in C.p.tschuktschorum). The iris is dark, the slender bill is blackish (often with a small area of yellow at the base), and the legs and feet are dull greenish-olive.
Non-breeding adult
This plumage is held between ~October and ~March/April, and most individuals observed in B.C. are in this plumage. The back, scapulars, and upperwing coverts are dark slate-grey, often with a slight purplish or bluish tone, with darker feather centres on the back and scapulars. The pattern of the rump, uppertail coverts, tail, and flight feathers is similar to that of the breeding-plumaged adult. The head and neck are wholly dark slate-grey, often with some fine pale or blackish streaking on the foreneck, extending onto the whitish underparts as bold, dense, dark grey spotting that is heaviest on the breast, sides, and flanks. The crown and lores are usually slightly darker than the rest of the head, and there is typically a paler grey area in front of (and sometimes around) the eye. Bare part colouration is generally similar to the breeding adult, but the bill has a brighter and more extensive yellowish or greenish-yellow base and the legs and feet are brighter yellowish.
First-winter immature
Birds in this plumage occur from ~October through ~March of the first year. This plumage is very similar to the non-breeding adult, but the rufous or reddish feather edges on the scapulars of juvenal plumage are retained, as are the flight feathers and wing coverts (which often appear worn relative to the rest of the plumage).
Juvenile
This plumage is held until July or August of the first year and is lost before fall migration; thus, it is extremely unlikely that birds in this plumage will be observed in B.C. This plumage is somewhat reminiscent of the breeding plumage (extensive rusty upperparts, etc.), but lacks the irregular dark patch on the upper breast, has fine grey streaking on the head, neck, and breast, has a buffy wash across the breast, has extensive rufous and buffy edges on the feathers of the upperwing coverts, and has narrow pale edges on the scapular feathers that form a pale ‘V’ or ‘braces’ on the upperparts.
Measurements
Total Length: 22-23 cm
Mass: 59-106 g
Source: Sibley (2000); Gill et al. (2002)