The red, green, and blue adult male Painted Bunting is almost unmistakable. The duller, green females and immature can be more confusing. In the United States and in northern Mexico, Painted Buntings are the only all-green birds with a sparrow-like (conical) bill. In southwestern Mexico, however, female Painted Buntings might be confused with female Orange-breasted Bunting (Passerina leclancherii).
It would be difficult to confuse the adult male Painted Bunting with any other species. The drabber, green females and immature can be more confusing. Throughout most of its range, the Painted Bunting is the only all-green bunting. The nonbreeding distribution of Painted Bunting overlaps, however, with resident Orange-breasted Buntings (Passerina leclancherii) in western Mexico. Orange-breasted Buntings occur from extreme southern Nayarit south along the coast to extreme western Chiapas, and inland in the Río Balsas drainage to western Puebla. Female and immature Orange-breasted Bunting are green above, and yellow below, and so have a superficial resemblance to Painted Bunting. In distinguishing the two species, note in particular the color of the lores, and of the underparts. Female and immature Orange-breasted Buntings have yellow lores that contrast with the green forecrown and sides of the face, and yellow, or more strongly yellowish-green, underparts; the lores of Painted Buntings are not noticeablely pale or contrasting, and the underparts are dull green or yellowish-green.
In Mexico and Central America, also take care not to confuse female Painted Bunting with female euphonias (Euphonia species). Euphonias are smaller than buntings, with much shorter tails; are less uniformly green; and typically range higher in the forest canopy, not relatively low near the ground.
Sexually dimorphic, but males do not acquire the distinctive adult plumage until a pre-basic molt in their second calendar year.
Adult male has a mostly dark blue head: blue extends from the forecrown back across the nape, down onto the sides to the head and the throat, with a narrow feathered red eye-ring and dusky lores. The scapulars and back are yellowish green. The rump and uppertail coverts are red. The flight feathers are dusky; the lesser wing coverts are mostly dull blue, the median wing coverts dull brown or dull red, and the greater wing coverts are green. The red underparts extend from the chin to the undertail coverts. This pattern is retained year-round.
Adult female is mostly dull green, paler and yellower below, especially in the center of the breast and belly. Lores duller. This pattern is retained year-round, although a small proportion of females in alternate plumage (worn roughly between March and September) may have some blue feathers on the head.
The Painted Bunting has a complex series of molts in the first year of life; for more details, see Molts (below; see also Thompson 1991a, Lowther et al. 1999, and Pyle 1997). Briefly, immature Painted Buntings resemble adult females in plumage. Immature females are average duller than adult females (often with a slight grayish undertone to the plumage). Immature males are brighter than immature females. A high proportion (approximately 40%) of young male Painted Buntings acquire some patches of blue feathers on the head by a prealternate molt early in the second calendar year, when the plumage otherwise remains mostly green. The multi-colored adult plumage is not attained until the following prebasic molt, late in the second calendar year.
There are interesting differences between the eastern and western populations in the timing of molts, relative to migration, in Painted Bunting. Birds of the eastern population undergo a prebasic molt on the breeding grounds, usually between September and November, and then migrate farther south to overwinter. Buntings of the western population, in contrast, move first to staging areas in southern Arizona and northwestern Mexico, where the prebasic molt takes place; following this molt, many individuals migrate farther south.
The sequence of molts and plumages is:
This plumage primarily is dull brown. Sexes are similar in appearance. This plumage is replaced quickly through a presupplemental molt, which usually is initiated about two weeks after hatching.
Attained by a presupplemental molt, which occurs on the breeding grounds; the period of this molt extends from the beginning of June to mid-October. The presupplemental molt replaces all of the body plumage, except for primary and greater coverts. Sexes are similar in this plumage, and resemble the adult female: the plumage primarily is olive-green above and yellow-green below, but with browner, retained juvenile rectrices, remiges, primary coverts, and greater coverts. The supplemental plumage is replaced through the prebasic I molt.
Basic I plumage:
The prebasic I molt is initiated when the bird is about two months old; the molting period extends from the beginning of September through the end of November. The prebasic I molt replaces all of the rectrices; the outer primaries (P6-P9); the inner secondaries (S5-S9); and all of the body plumage, except for some or all of the primary coverts. Sexes are similar in this plumage, and resemble the adult female, except for the retained inner primaries, outer secondaries, and primary coverts. The great majority of birds in the eastern population complete the prebasic molt on the breeding grounds, prior to migrating south; in contrast, many birds in the western population migrate first to staging areas where the prebasic molt takes place, before after which molt migration resumes to take birds on the wintering grounds. The Basic I plumage is replaced through the prealternate I molt.
Alternate I plumage:
The prealternate I molt primarily takes place on the wintering grounds, between mid December and mid May. The full extent of this molt is not well-known. Only body plumage is involved during the prealternate 1 molt, but probably only some of the entire body plumage is replaced; this molt is most apparent on the head, where small patches of blue feathers may appear. The appearance of blue on the head is more prevalent in males (40% or more of males, compared to 5% of females). Other than in the plumage of the head, the sexes are similar in Alternate I plumage, and greatly resemble the adult female. This plumage is replaced through the Definitive Prebasic molt.
Definitve Basic plumage:
The definitive prebasic molt occurs from the beginning of August through mid October. As with the prebasic I molt, most individuals of the eastern population complete this molt on the breeding grounds, prior to migration; many birds of the western population do not undergo the definitive basic molt until after migrating to staging areas, away from the breeding grounds. This molt is complete. The Definitive Basic plumage of the male is the "adult male" plumage, described above (Description), and is very similar to the Definitive Alternate plumage. The plumage of the female is similar to that of the female in Definitive Alternate, but has no blue in the plumage of the head. The Definitive Basic plumage is replaced through the definitive prealternate molt.
Definitive Alternate plumage:
The definitive prealternate molt takes place from around the beginning of January until the end of May. The molt primarily takes place on the wintering grounds. The Definitive Alternatec plumage of the male is the "adult male" plumage, described above (Description); and is very similar to the Definitive Basic plumage. The Definitive Alternate plumage of the female is the "adult female" plumage, described above; it is very similar to the Definitive Basic plumage, but some females in this plumage have a few blue feathers on the head.
The iris is dark brown; the bill is dark brown or blackish; and the tarsi and toes are gray, brown, or dusky brown.
A medium-sized bunting.
Length: 12-13 cm (4 ¾-5")
Mass: 13-19 g