WatchList Species Account for ‘Akiapola’au (Hemignathus munroi)

Qualifies for the list as a Red List Species

Photo: Jack Jeffrey

Endemic to the island of Hawaii, the ‘Akiapola’au was described by early naturalists as common to abundant throughout its range, but clearing of lower elevation forests during the 1900s split the population into four subunits in remnant native forest above 1500 meters. Only one of these four subpopulations survives in significant numbers, with the other three subpopulations reduced to an estimated 44 birds, 20 birds, and 3 birds respectively. In 1990-95 the total numbers of the bird were estimated at 1,163 individuals. In behavior, it occupies the woodpecker niche, creeping along trunks and branches and probing for grubs and various arthropods within the bark. Its tools for doing so are entirely different from that of a woodpecker; this honeycreeper has a long downward-curving upper mandible it uses to probe and a short awl-like lower mandible it uses to tap. It forages mainly on the koa tree, selecting lichen-covered and dead branches to search for arthropods. The bird also drinks sap from shallow wells it drills in live bark of ‘ohi’a-lehua trees.

Threats include grazing and logging that have degraded or destroyed much of its habitat, predation by introduced mammals including feral cats, which are ubiquitous in the bird’s habitat, rats, and native raptors; other threats include mosquito-borne avian diseases and depletion of the bird’s prey by introduced predatory and parasitic insects. Global climate change will potentially facilitate mosquitoes moving to higher elevations, thus decreasing even further the habitat for this and other native Hawaiian passerines. Generally the Akiapola’au raises only one young a year, which remains with its parents for many months. Because it has such a slow reproductive rate, it is slow to recover when its populations are reduced. Among the protected sites with significant populations are Hakalau Forest National Wildlife Refuge and Ka’u Forest Reserve.

Habitat restoration work is underway for the species; sheep and mouflon have been removed from Mauna Kea, allowing regeneration of the mamane forest, while removal of cattle and fencing have been used at other reserves. Conservation measures that should be taken include protection of remaining old-growth native forest above the zone where mosquitoes are known, removal of all feral ungulates, and captive propagation. Reforestation of degraded sites that could support Akiapola'au should also be initiated.