SPECIES

Kauai Nukupuu Hemignathus hanapepe Scientific name definitions

Thane K. Pratt, Steven G. Fancy, and C. John Ralph
Version: 1.0 — Published March 4, 2020
Text last updated January 1, 2001

Plumages, Molts, and Structure

Plumages

Plumage colors taken from photographs of live birds (‘Akiapölä‘au) and specimens (all taxa; Pratt et al. 1994, TKP and J. Lepson unpubl.).

Hatchlings

No information.

Juvenile Plumage

Plumage of individuals of both sexes varies somewhat in amount of green. Individuals dorsally greenish gray to grayish green, with variable, faintly darker scalloping on crown and cheeks. Margins of wings and tail feathers more yellowish green. Greater wing coverts with faintly paler tips. Lores blackish gray. Underparts very pale yellowish gray with variable dark scalloping and smudging. Flanks pale greenish gray, with or without smudging.

Basic I Plumage

(Appears to include Basic II plumage for some males at least.) Plumage of individuals of both sexes varies in amount of yellow and green, but usually more yellowish than Juvenile plumage, and lacks scalloping and smudging, although some scalloped feathers may be retained on the face. Individuals dorsally greenish gray to grayish green. Margins of wings and tail feathers more yellowish green. Some greater wing coverts with faintly paler tips. Lores blackish gray. Chin or chin and throat dull to bright yellow. Rest of underparts pale yellowish gray or yellowish green, paler on the belly. Flanks pale greenish gray or grayish green.

Definitive Basic Plumage

Male. Crown, nape, line behind eye, and tips of ear coverts yellowish green. Back, wing coverts, margins of wing, and tail feathers yellowish green with less chroma (more grayish), but chroma increasing again gradually on rump to yellowish green. Loral patch, bristles at base of bill, and (to varying degree) eye-ring black. Superciliary stripe and cheeks greenish yellow. Cheeks, chin, and upper throat yellow shifted in hue slightly towards orangish yellow. Lower throat, breast, and belly paler yellow. Flanks and undertail coverts yellowish green. Color of males varies slightly in chroma and value, from bright to dull yellow. A banded male at least 13 yr old had lost his original bright yellow color and was instead dull olive (PIERC unpubl.).

Female. Plumage of individuals varies slightly in amount of yellow and green, but usually more yellowish than Juvenile plumage, and without scalloping and smudging, although some scalloped feathers may be retained on the face. Upperparts grayish green. Margins of wings and tail feathers more yellowish green. Lores and bristles at base of bill blackish gray. Chin and throat and upper breast yellow. Rest of underparts pale yellowish gray (some individuals, possibly in Definitive plumage, yellowish green), paler on the belly. Flanks pale greenish gray or grayish green.

Molts

‘Akiapölä‘au and the 3 Nukupu‘u taxa all undergo a partial Prebasic I molt (Pratt et al. 1994, TKP and J. Lepson unpubl.). In ‘Akiapölä‘au, at least, this molt is initiated soon after fledging. Thus, young birds following parents may be in either Juvenile or Basic I plumage. Female ‘Akiapölä‘au pass through a distinctive Basic I plumage before attaining Definitive Basic plumage in their second year; unclear whether males pass through 1 or 2 subadult plumages. Definitive Prebasic molt complete for both species, although unknown for O‘ahu Nukupu‘u; remigial molt proceeds from innermost to outermost feathers.

Molting ‘Akiapölä‘au can be found at any time of year (Ralph and Fancy 1994c). Pratt et al. (Pratt et al. 1994) reported a broad annual peak in molt Feb–Jul (n = 162) that overlapped the birds' breeding season (Figure 8). Significance of nearly complete overlap between breeding and molting phenology unclear. Do individual ‘Akiapölä‘au molt over a longer time than other honeycreepers? Do they molt while breeding? Is there simply weak synchrony in breeding and molting within the population?

Of only 6 molting Nukupu‘u specimens collected from all islands, 5 were taken in Jul–Sep (PIERC unpubl.).

Bare Parts

Bill And Gape

‘Akiapölä‘au and All Three Nukupu‘u. Bill of adult males and females glossy black, although in some specimens paler (brownish black) at the base of mandible. In O‘ahu Nukupu‘u, base of upper and lower mandible always paler. Bill of immature birds varies, probably with age, from pale pinkish gray to brownish black, generally paler towards the base. Gape in males black and in females and immature individuals variably paler, being pinkish or orangish gray.

Iris

‘Akiapölä‘au, Kaua‘i Nukupu‘u, and Maui Nukupu‘u (and Presumably O‘ahu Nukupu‘u). Dark brown.

Legs And Feet

‘Akiapölä‘au. Gray. Pads of feet paler pinkish gray.

Nukupu‘u. Noted on specimen labels of adult male Kaua‘i Nukupu‘u as “black” (S. Wilson) or “slaty black” (G. Munro). Rothschild (Rothschild 1893a), however, described the color of fresh specimens of Kaua‘i and Maui nukupu‘u of all ages and sexes as similar to ‘Akiapölä‘au.

Measurements

Linear Measurements

See Appendix 1 . Taxa differ in size and proportions (see Systematics, above). 'Akiapölä'au show statistically significant but very slight variation over distance and elevation (Pratt et al. 1994). In 'Akiapölä'au (Pratt et al. 1994) and all 3 Nukupu'u, males larger than females with bills disproportionately longer, a character useful for sexing birds. Bill of male 'Akiapölä'au continues to increase in length between Basic I and Definitive Basic plumages; data insufficient for females; unstudied for Nukupu'u (Pratt et al. 1994).

Mass

See Appendix 1 for 'Akiapölä'au. No data for Nukupu'u.

Akiapolaau Male 'Akiapola'au. Hakalau Forest NWR, Hawaii. June 2000
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Male 'Akiapola'au. Hakalau Forest NWR, Hawaii. June 2000

; photographer Jack Jeffrey

Akiapolaau Female Akiapolaau. Hakalau Forest NWR, Hawaii. Dec 1994
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Female Akiapolaau. Hakalau Forest NWR, Hawaii. Dec 1994

; photographer Jack Jeffrey

Akiapolaau Fig. 8. Annual cycle of 'Akiapölä'au.
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Fig. 8. Annual cycle of 'Akiapölä'au.

Figure 8. Annual cycle of ‘Akiapölä‘au. (No data for Nukupu‘u.) Conceptually, the diagram does not reflect well the seasonality of ‘Akiapölä‘au molting and breeding, which can occur at any time of year. More data are needed to accurately show peaks of activity. The complete overlap of peak molting and breeding, as currently understood, seems unlikely.

Akiapolaau Figure 8. Annual cycle of 'Akiapölä'au.
Enlarge
Figure 8. Annual cycle of 'Akiapölä'au.

(No data for Nukupu‘u.) Conceptually, the diagram does not reflect well the seasonality of ‘Akiapölä‘au molting and breeding, which can occur at any time of year. More data are needed to accurately show peaks of activity. The complete overlap of peak molting and breeding, as currently understood, seems unlikely.

Recommended Citation

Pratt, T. K., S. G. Fancy, and C. J. Ralph (2020). Kauai Nukupuu (Hemignathus hanapepe), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.nukupu2.01