Plumages, Molts, and Structure

Descriptions based on examination of specimens (n = 24; 6 juveniles, 18 adults) by JTF and T. Pratt at BPBM and from 15 birds mist-netted in Alaka‘i Swamp by T. Snetsinger and C. Herrmann. Juveniles readily distinguished from adults by prominent facial markings. Most recent specimen in BPBM, adult male collected in 1987, used to determine plumage coloration. Colors from faded specimens collected in 1890s to early 1900s also noted. Capitalized, numbered colors reference to Smithe (1975–1981). Molts poorly known.

Hatchlings

Data from 1 nest with 2 nestlings of undetermined age (Eddinger 1972 Eddinger, C. R. (1972). Discovery of the nest of the Kauai Akepa. Wilson Bulletin 84:95-97. Close ). Bicoloration of adults also apparent in nestlings. Incoming Juvenile feathers on wings and back brownish green. White natal down interspersed on back and head. Incom-ing Juvenile feathers on underparts cream-white.

Juvenile Plumage

No information on Prejuvenile molt. Juveniles distinguished from adults by white patch around eye or “spectacles” that sometimes connects on forehead above base of upper mandible. Wing-bars, noticeable on juveniles in field and from museum specimens, created by light gray or off-white tips on greater and median wing coverts. Not present in all individuals, possibly due to wear of covert tips or presence of a second-year (SY) plumage. Plumage coloration otherwise indistin-guishable from adult (see below).

No information on Prebasic I molt in this species. In other Hawaiian honeycreepers this is a partial molt that occus in first few months after fledging (Amadon 1950 Amadon, D. (1950). The Hawaiian Honeycreepers (Aves, Drepaniidae). Bulletin of the American Museum of Natural History 95:151-262. Close , Baldwin 1953 Baldwin, P. H. (1953). Annual cycle, environment and evolution in the Hawaiian honeycreepers (Aves: Drepaniidae). University of California Publications in Zoology 52:285-398. Close ).

Definitive Basic Plumage

Hawaiian honeycreepers are known to have 1 (Prebasic) molt/year. Individuals in molt in their second year probably undergoing Definitive Prebasic molt. SY individuals with characteristic spectacles of juveniles seen molting out of white superciliary feathers as early as Mar (T. Snetsinger pers. comm.). Six museum specimens collected in Feb, Mar, and May undergoing same molt process around eye with gray feathers replacing white. Only 1 of 23 museum specimens with partial or full spectacles exhibited flight-feather molt. P1–3 were in molt, suggesting a SY bird undergoing Definite Prebasic molt. This molt pattern follows sequence P1–P9 typical of Hawaiian honeycreepers, although concurrent molt of secondaries (Baldwin 1953 Baldwin, P. H. (1953). Annual cycle, environment and evolution in the Hawaiian honeycreepers (Aves: Drepaniidae). University of California Publications in Zoology 52:285-398. Close ) not occurring.

No discernible difference in coloration of males or females based on museum specimens, nor has a difference been determined for birds in the field. Forehead, crown, nape, and mantle Olive (30). Rump close to Olive-Gray (42). Chin and throat white, tinged Smoke Gray (44), breast white, tinged Cream Color (54), flanks Smoke Gray (45). In older specimens: chin and throat white; breast Cream Color (54), belly white, tinged with Cream Color (54); flanks and undertail coverts Light Drab (119C) to Olive Brown (28, 29); back Hair Brown (119A). Overall color on back, wings, and tail change in specimens as they age, from olive to brown, but edging on fresh primaries, secondaries, and tail feathers of many specimens remain grayish-green. Olive or green plumage not apparent on most ‘Akikiki in the field; upperparts appear gray.

Bill And Gape

Bill short and slightly decurved. Juvenile and adult bills pale pink to light gray but specimens described by Wilson and Evans (Wilson and Evans 1890 Wilson, S. B. and A. H. Evans. (1890). Aves Hawaiienses: the birds of the Sandwich Islands. London: R. H. Porter. Close ) were “light brown, tinged with pink.” Colors on museum specimens not representative of colors seen on birds in field. Bill on museum specimens ranges from Tawny Olive (223D) to brownish yellow. Nestling has bright-pink mouth and lining of bill edged with yellow (Eddinger 1972 Eddinger, C. R. (1972). Discovery of the nest of the Kauai Akepa. Wilson Bulletin 84:95-97. Close ).

Iris

Noted as brown or dark brown on several specimen labels at BPBM, described by Wilson and Evans (Wilson and Evans 1890 Wilson, S. B. and A. H. Evans. (1890). Aves Hawaiienses: the birds of the Sandwich Islands. London: R. H. Porter. Close ) as “dark hazel”; same coloration as most Hawaiian honeycreepers.

Legs And Feet

Dull pink to light gray in field. Museum specimen labels at BPBM indicate “gray” and “grayish brown.” Recently collected specimen has Cinnamon Brown (33) legs and feet; coloration of older specimens is Robin Rufous (340).

See Appendix 1 and Appendix 2 for linear measurements and mass. Linear measurements from museum specimens indicate males typically larger than females for all characters. All measurement methods standard: bill (exposed culmen)—chord of the culmen from tip of upper mandible to implantation of feathers at base; bill width—straight line meas-ured across top of upper mandible at front edge of feathering; bill depth—measured top to bottom as base of bill at front edge of feathering; wing—unflattened wing chord; tail—from point between central pair of rectrices where they emerge to tip of longest rectrix; tarsus—from tibiotarsus-tarsometatarsal joint to base of middle toe.