Pink-headed Warbler is mostly pink in color, although as its name implies, the head is more pinkish than is the body. The plumage of the head and chest is silvery pink, and the body plumage is reddish pink, darker and redder above. The wings and tail are darker. The sexes are similar, but juveniles differ; the juvenile has an entirely pinkish cinnamon-brown body, darker and redder above, and with two pinkish wing bars.
Pink-headed Warbler is very distinctive within its range. The allopatric Red Warbler (Cardellina rubra) is similar is size and in egg color, but the plumage of Red Warbler is a deeper and more uniform red; the head and breast of Red Warbler also are red, not pinkish, except for white or gray auriculars.
The following description of the adult plumage is based on Ridgway (1902):
Adult: Sexes similar. Head, neck, and breast rose pink; there is a satiny gloss to the plumage, and the colors may vary depending upon the light, appearing nearly white under some conditions. The color deepens on the forehead, lores and the suborbital region. Also, the bases of the feathers of the head, neck and breast are dusky. Back and scapulars dark brownish red or deep carmine. Uppertail coverts dark brownish red, like the back, but with paler red tips. Remiges and rectrices dusky with narrow, indistinct grayish red edgings, more distinct on the tertials. Lesser wing coverts dark brownish red or deep carmine (the same as the back). Median wing coverts dusky, tipped with pinkish red; greater wing coverts dusky, edged with deeper, duller red. Underparts poppy red, the tips of the feathers sometimes with indistinct pale pinkish margins.
Juvenile: "Overall pinkish cinnamon-brown, darker and redder above, wings and tail blackish, edged dark red, with 2 pinkish wingbars" (Howell and Webb 1995); "cinnamon-brown or tawny-brown, with maroon tinge n upperparts, brown wings and tail, tawny wingbars on greater and median coverts" (Curson 2010).
Little information; no molt detected in March-April or in October.
Iris: dark brown
Tarsi and toes: yellowish brown
Total length: 12.5-13.5 cm (Howell and Webb 1995), 13 cm (Curson 2010)
Linear measurements (from Ridgway 1902):
Wing length, male: mean 60.3 mm (range 58-63 mm, n = 7)
female: mean 57.8 mm (range 57-59 mm, n = 5)
Tail length, male: mean 54.8 mm (range 52-56.5 mm, n = 7)
female: mean 54.4 mm (range 53-56 mm, n = 5)
Bill length (exposed culmen), male: mean 8.5 mm (range 8-9 mm, n = 7)
female: mean 8.1 mm (range 7-9, n = 5)
Tarsus length, male: mean 19.3 mm (range 19-20 mm, n = 7)
female: mean 18.8 mm (range 18-19.5 mm, n = 5)
Mass: mean 8.14 g (n = 5)