Akiapola'au  (Hemignathus munroi)

Classified as Endangered (EN) on the IUCN Red List (1) and as Endangered by the United States Fish and Wildlife Service (3).

This odd-looking bird has a rotund body, a large head, and an oversized, strongly-curved upper bill. It has yellow-green upperparts and yellow underparts, with an orange hue to the face and breast (2). Adult males sing with a short and rapid warbling song and both adults call with a variety of short whistle notes (2) (4).

Endemic to Hawaii in the Hawaiian Islands, the ‘Akiapola’au was previously widespread on the island but is now patchily distributed. Surveys undertaken in 1990 to 1995 estimated that only around 1,160 ‘Akiapola’au remained (2).

Found in mature koa and ‘ohi’a forest between 1,300 and 2,900 metres above sea level (2).

The ‘Akiapola’au is a honeycreeper which drills three to five millimetre deep holes in ‘ohi’a trees (Metrosideros polymorpha) to drink the sap within (5). It also uses its unique bill to pick out arthropods from beneath the bark of koa (Acacia koa) and other species (6). Individuals are faithful to certain trees, with males feeding on the trunks and large branches, whereas females creep along small branches and twigs. Males have slightly longer bills, enabling them to peck into the thicker bark of larger branches (7). This species makes a softer version of the tapping noise characteristic of woodpecker species in other parts of the world (4) (8).

This monogamous species occupies very large territories (2) (6), breeding at any time of year (3), but mainly between January and June (9). It builds a nest at the end of a leafy branch of the ‘ohi’a tree, which remain home to the chick for a long period before it is mature enough to fledge (2).

As with many species on Hawaii, the ‘Akiapola’au is threatened by deforestation and habitat degradation due to livestock grazing, and is also preyed upon by introduced rats and feral cats. The introduction of mosquitoes to Hawaii has resulted in the spread of avian diseases which confine many bird species, including the ‘Akiapola’au, to higher elevations. This species has a low reproductive rate and is slow to recover from population reductions (2).

Relatively large ‘Akiapola’au populations are found within the boundaries of Ka’u Forest Reserve and Hakalau Forest National Wildlife Refuge. Outside these areas some habitat is being restored (2), and young koa forests on the volcano of Mauna Loa now support high densities of Akiapolaau (6). It is hoped that the ‘Akiapola’au might be re-introduced into other newly restored habitat. Plans to restore corridors of habitat between areas of forest occupied by the ‘Akiapola’au may reduce the damaging effects of habitat fragmentation, including inbreeding depression (2).

View information on this species at the UNEP World Conservation Monitoring Centre.

For further information on the Akiapola’au see:

• BirdLife International:
  www.birdlife.org/datazone/search/species_search.html?action=SpcHTMDetails.asp&sid=8912&m=0