Plumages, Molts, and Structure

Capitalized, numbered colors below from Smithe 1975 Smithe, F. B. (1975). Naturalist's Color Guide. American Museum of Natural History, New York, NY, USA. Close .

Hatchlings

Altricial; psilopaedic (little or no down); skin reddish pink. Some pale gray beige down present on dorsal surface (Peregrine Fund unpubl. data).

Juvenile Plumage

No information on Prejuvenile molt. Description of Juvenile plumage based on 1 museum specimen and photographs of 1 fledgling (USGS/BRD, HB). Juvenile plumage similar to Definitive Basic (adult) plumage but paler overall; crown, back, remiges, and rectrices are somewhat lighter Grayish-Olive (43). Supercilium, cheek, chin, throat, and upper breast dull Olive (30), with faint Yellow (52) wash; lower breast, belly, and undertail-coverts dull white. Lores gray. Remiges and rectrices dusky gray, with Olive margins. Greater wing coverts sometimes paler at tip, producing a faint wing-bar. Not known whether sexes differ in Juvenile plumage.

Basic I Plumage

Prebasic I molt partial; body feathers replaced, (but Juvenile remiges and rectrices retained); exact sequence of feather replacement not known. Basic I plumage similar to Definitive Basic, but head and back slightly duller olive; yellow paler and restricted on underparts more to breast. No Alternate plumages known (USGS/BRD, PEB).

A distinct Basic II plumage may occur, but information is inconclusive (see below).

Definitive Basic Plumage

Definitive Prebasic molt complete; primaries and inner secondaries (S9–S7 = tertials) precede secondaries, but with overlap. Primaries molt from inner (P1) to outer (P9), at rate of 3 feathers per month (PEB). Secondaries molt from outer (S1) to inner (S6), tertials (inner secondaries) molt from inner (S9) to outer (S7). Tail molt concurrent with flight-feather molt; replaced from inner (R1) to outer (R6). Rate of molt for secondaries and tail not known. Body molt concurrent with flight-feather molt, but continues for some additional period; sequence unclear (USGS/BRD, PEB, HB). Birds in molt are seen from early May, with a peak Jul through Sep, continuing through Nov (see Figure 3). The following plumage descriptions are based on museum specimens and birds caught for banding (PEB, HB).

Male. Forehead and front of crown Yellowish Olive-Green (50); remainder of crown Olive-Green (46), with distinct Yellowish Olive-Green edging. Supercilium Spectrum Yellow (55); broad, extending from base of upper mandible to nape. Postocular stripe Yellowish Olive-Green. Cheeks, chin, and throat Spectrum Yellow. Lores Dark Neutral Gray (83) to black; feathers covering nares Brick Red (132A) to Dark Gray; rictal bristles black. Nape and back variable from dull Olive-Green to Yellowish Olive-Green. Rump brighter Yellowish Olive-Green than back. Breast and upper belly Spectrum Yellow; lower belly between legs to vent variable, from dull Sulfur Yellow (157) to off-white with a dull Sulfur Yellow wash. Undertail-coverts slightly brighter Sulfur Yellow than lower belly. Flanks bright Spectrum Yellow, becoming mixed with Olive-Green toward rear. Primaries, secondaries, and tertials Dark Neutral Gray, edged on outer web with Yellowish Olive-Green. Lesser-, median-, and greater coverts gray, with broad Yellowish Olive-Green margins; primary coverts have little or no olive edging. Wing-lining white, with yellowish wash. Rectrices Dark Neutral Gray; outer margins Yellowish Olive-Green.

Female. Forehead Olive-Gray (42). Crown Olive-Gray mixed with Grayish Olive (43). Supercilium off-white, with slight yellowish wash; broad, extending from base of upper mandible to nape. Postocular stripe Olive-Gray. Cheeks Olive-Gray, with slight yellow wash. Chin and throat Olive-Gray to Smoke Gray (42–44). Lores Glaucous (80); feathers covering nares pale Brick Red; rictal bristles black. Nape and back variable from Olive-Gray to Grayish Olive. Rump Yellowish Olive-Green. Breast and upper belly dull Sulfur Yellow (157); lower belly dull Sulfur Yellow, with some dull yellowish white feathers. Lower belly to vent dull yellowish white. Undertail-coverts white to very dull yellow. Flanks dull Sulfur Yellow, becoming mixed with Citrine (51) toward rear. Primaries, secondaries, and tertials Dark Neutral Gray, edged on outer web with Citrine. Lesser-, median-, and greater coverts gray, tipped and broadly edged on outer web with Citrine; primary coverts have little or no olive on outer edging. Wing-lining white, with yellowish wash. Rectrices Dark Neutral Gray; outer edges Citrine.

Faint yellowish wing-bars, formed by pale tips on median- and greater coverts, have been recorded for several dull birds, but their reliability in indicating age or sex has yet to be determined. Such birds may be exhibiting a distinct Basic II plumage (wing-bars are a Juvenile and Basic I and II characteristic in some other honeycreepers, such as Maui ‘Alauahio; HB, PEB).

Bill And Gape

Juvenile. Upper mandible Medium Neutral Gray (84), grading into medium yellow brown along tomium; lower mandible medium yellow brown. Rictal flanges yellow. Inside of mouth True Purple (101).

Definitive, Male. Culmen Blackish Neutral Gray (82), fading to Medium Neutral Gray (84) along lateral surfaces of upper mandible; tomium very pale Beige (219D). Lower mandible very pale Beige, sometimes with grayish flush. Rim pink, with Sulfur Yellow (157) cast.

Definitive, Female. Culmen Dark Neutral Gray (83), becoming Blackish Neutral Gray toward tip; tomium very pale Beige. Lower mandible very pale Beige, sometimes with grayish flush. Blood vessels in lower mandible visible in both sexes. Rictal flanges pink, with yellow cast.

Iris

Dark brown. No known sex or age differences.

Legs And Feet

Medium Neutral Gray to Dark Neutral Gray. Pads of feet dull whitish yellow.

Sexually dimorphic in wing and bill length; male distinctly larger than female (Table 1). During field observations, experienced observers can often use bill size to determine sex (PEB, USGS/BRD).