Justification of Red List Category
This species is classified as Vulnerable because it has a very small range. It is restricted to two mountain ranges on one island, and, although it has apparently adapted to non-native habitats, it remains at risk from the effects of exotic taxa, especially the possible introduction of disease-carrying mosquitoes capable of tolerating the cooler climate at high altitudes.
The population is estimated at 20,000-60,000 birds, roughly equivalent to 13,000-40,000 mature individuals, but surveys on O`ahu, unlike those on other Hawaiian islands, have not been systematic, and these estimates may be too high (R. Shallenberger in litt. 1999).
Christmas bird counts indicate a population decline from 1958 to 1985 (Jacobi and Atkinson 1995; Lindsey et al. 1998), but more recent information indicates that the population may be stable and even increasing in some areas (Lindsey et al. 1998).
Hemignathus flavus is endemic to O`ahu in the Hawaiian Islands (USA). It originally occurred throughout the island, but is now restricted to the two mountain ranges. In the Wai`anae Mountains, it is uncommon and sparsely distributed, mostly above 500 m elevation. In the southern and central Ko`olau Mountains, it is locally common, occurring from the summits occasionally down to 30 m in valleys, but it becomes increasingly rare northwards and is practically absent from the northern tip of the range (Lindsey et al. 1998). The population is estimated at 20,000-60,000 birds (Jacobi and Atkinson 1995, Lindsey et al. 1998), but surveys on O`ahu, unlike those on other Hawaiian islands, have not been systematic and these estimates may be too high (R. Shallenberger in litt. 1999). Christmas bird counts indicate a population decline over the period 1958-1985 (Lindsey et al. 1998), but more recent information indicates that the population may be stable and even increasing in some areas (Jacobi and Atkinson 1995, Lindsey et al. 1998).
It has adapted relatively well to forests of non-native trees, but is most abundant in native forests, particularly where koa trees dominate (Lindsey et al. 1998). It nests and forages in urban areas where enough trees grow (Lindsey et al. 1998). Little is known about its diet, but it probably feeds primarily on small insects and other arthropods, taking nectar and fruit as secondary food sources (Lindsey et al. 1998).
Feral ungulates and introduced predators are likely to have contributed to historical declines (Lindsey et al. 1998) and to be continuing limiting factors. Diseases spread by introduced mosquitoes were probably also a major factor, but some populations have apparently developed some degree of resistance to avian malaria, and this may explain recent population increases in lowland areas (Lindsey et al. 1998).
Conservation Actions Underway
No specific conservation measures are known for this species.
11 cm. Small honeycreeper with short, down-curved bill. Male all golden-yellow below, sharply contrasting with olive-green upperparts. Black lores, with yellow supraloral spot. Female greenish-grey above, pale yellowish-white below, with prominent wing-bars of same colour. Dark grey lores, yellowish-white supraloral spot. Juvenile male duller than adult, with two buffy wing-bars. Similar spp. Male O`ahu `Alauahio Paroreomyza maculata has straight bill, bold yellow stripe over eye and dark stripe through eye. Female has dark line behind eye only and pale lores. Introduced Japanese White-eye Zosterops japonicus has straight bill, bold white eye-ring. Voice Song a vigorous trill of single notes. Call a short cat-like buzzy note. Hints Easily seen at fairly low elevation around flowering trees in mountains behind Honolulu.
Text account compilers
Benstead, P., Derhé, M., Stattersfield, A., Stuart, T., Taylor, J.
Shallenberger, R., Fretz, S., Gorresen, M., VanderWerf, E., Woodworth, B., Camp, R.
BirdLife International (2020) Species factsheet: Chlorodrepanis flava. Downloaded from http://www.birdlife.org on 23/10/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 23/10/2020.