Justification of Red List Category
This species is Endangered owing to its very small, severely fragmented and contracting range, where habitat loss and degradation continues owing to feral ungulates and pigs. It may be affected by diseases carried by introduced mosquitoes and has recently disappeared from one area and is declining elsewhere.
Surveys in 1976-1983 estimated the population at c.12,500 individuals, however this number has since declined overall (E. VanderWerf in litt. 1999). The population is therefore estimated in the range 2,500-9,999 mature individuals. This equates to 3,750-14,999 individuals in total, rounded here to 3,500-15,000 individuals.
Since surveys in 1976-1983, the small Hualalai population has disappeared (E. VanderWerf in litt. 1999), the low elevation Hamakua population may have disappeared (or perhaps is just seasonal there; J. Lepson in litt. 2000), and the two other smaller populations are thought to be declining (E. VanderWerf in litt. 1999). In addition, survey results in the Central Windward region from 1977 to 2003 show apparent declines in some parts of the region (Gorresen et al. 2005).
Oreomystis mana is endemic to Hawai`i in the Hawaiian Islands (USA), where it was formerly widespread, but now occurs as three disjunct populations. Surveys in 1976-1983 estimated the population at c.12,500 individuals with 2,100 in Kau, 10,000 in Hamakua, 75 in central Kona, and 200 on north-west Hualalai (Scott et al. 1986). The small Hualalai population has since disappeared (E. VanderWerf in litt. 1999), the low elevation (700 m) Hamakua population may have disappeared (or perhaps is just seasonal there [J. Lepson in litt. 2000]), and the two other smaller populations are thought to be declining (E. VanderWerf in litt. 1999). The Kau population still occupies the extent of range recorded in the 1970s, but it has contracted from higher elevations (T. Pratt in litt. 2007), and the species appears to have declined between 1977 and 2003 in some parts of the Central Windward region (Gorresen et al. 2005).
It occurs principally in wet and mesic koa-`ohi`a forest mainly between 1,000 and 2,300 m, with the highest densities mainly between 1,500 and 1,900 m (Ralph and Fancy 1994). Historical and occasional recent sightings in dry mamane forest suggest that some individuals may move seasonally, or that a very small population may inhabit dry forest year-round (Scott et al. 1986, Snetsinger 1995-1996). It nests in koa trees (in cavities and open cup nests [J. Lepson in litt. 2000]) as well as in tall `ohi`a trees, and the species has successfully bred in disturbed woodland (VanderWerf 1998a).
It may have declined owing to habitat loss and degradation (Ralph and Fancy 1994, VanderWerf 1998a), although its ability to breed in some types of disturbed forest suggests that habitat alteration is not the primary factor limiting its current distribution (VanderWerf 1998a). Feral ungulates, particularly pigs, have severely degraded native forests and facilitate the spread of alien plants and disease-carrying mosquitoes (Scott et al. 1986, Pratt 1994). In 1992, there were pox and malaria epidemics among birds at Hakalau and at mid-elevations (Jacobi and Atkinson 1995, VanderWerf 2001). Nest-predation by introduced rodents and nest-site limitation are additional threats (Ralph and Fancy 1994, VanderWerf 1998a).
Conservation Actions Underway
The Hakalau Forest National Wildlife Refuge was established to protect some of the best remaining habitat for this and other threatened honeycreepers (Scott et al. 1986, Ralph and Fancy 1994). The species has become extinct in the montane sections of the Hawai`i Volcanoes National Park (T. Pratt in litt. 2007). However, in 2003, the Kahuku unit was added to the national park, incorporating much of the species's habitat in the Kau area (T. Pratt in litt. 2007). The fencing and eradication of feral goats began in the national park in 1971 (Stone and Loope 1987), and the removal of cattle, mouflon sheep and pigs from the Kahuku unit is expected to benefit the species (T. Pratt in litt. 2007). During the 1990s, efforts were made to reduce the feral pig population by Hawaiian conservation authorities and private landowners (Anderson and Stone 1993). Planting of koa and other native plants began in the early 1990s, and at the Kapapala Forest Reserve and the Pu`u Wa`awa`a Forest Bird Sanctuary, cattle have been removed and fences erected (USFWS 2003). The Zoological Society of San Diego is developing techniques for rearing Oreomystis creepers from eggs and breeding them in captivity, including the Hawai`i Creeper, at the Keauhou Bird Conservation Center (USFWS 2003). The Hawai`i Creeper has been successfully propagated in captivity, and release of the captive population is planned (USFWS 2003, P. Roberts in litt. 2007).
11 cm. Inconspicuous bark-picker with conical, very slightly downcurved bill. Adults dull grey-green, paler below with white chin and throat, pale grey bill, and dark grey mask from base of bill to behind eye. Juvenile similar but with pale face and white superciliary. Similar spp. Hawai`i `Amakihi Hemignathus virens female and juvenile similar, but throat never white, darker bill and narrower, more curved, dark lores. Voice Song a rattling, descending trill. Call an upslurred sweet. Juveniles following adults utter chatter of irregularly spaced notes whi-whit, whi-whi-whit etc. Hints Still found in most high-elevation native forests but easily overlooked. Joins mixed-species flocks in late summer and autumn.
Text account compilers
Benstead, P., Derhé, M., Harding, M., Isherwood, I., Stattersfield, A., Stuart, T., Taylor, J.
Lepson, J., Gorresen, M., Camp, R., Fretz, S., Roberts, P., Woodworth, B., Pratt, T., VanderWerf, E.
BirdLife International (2020) Species factsheet: Manucerthia mana. Downloaded from http://www.birdlife.org on 13/07/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 13/07/2020.