The island of Hawai'i is part of the US state of Hawaii (which also includes EBAs 216 and 217) and is larger than all other islands in the archipelago combined. It is the youngest island of the Hawaiian chain, with five volcanoes: Kohala, Mauna Kea (at 4,205 m, the highest mountain), Hualalai, Mauna Loa and Kilauea, the last three having erupted in historic times.

Hawai'i was originally largely covered in forest and woodland, with open areas above the treeline at c.3,000 m and very extensive lava flows where forest survives in small patches (kipukas). Three extant main types of wooded habitat, important for restricted-range species, can be recognized: rain forest in wetter areas (where the myrtaceous tree ohia Metrosideros polymorpha is dominant), drier woodland (where koa Acacia koa is dominant) and a second type of dry woodland usually at high elevations (where the legume mamane Sophora chrysophylla and naio Myoporum sandwicense dominate).

Hawai'i has a particularly distinctive avifauna with five endemic genera: Chaetoptila, Chloridops, Ciridops, Loxioides and Rhodacanthis. Most of the restricted-range bird species occur in forest and woodland, and many are found largely above c.500 m, although originally they are likely to have occurred in the lowlands too, e.g. Psittirostra psittacea (found only on Mauna Loa) and Loxioides bailleui (only on Mauna Kea), which today are confined to upland forest.

A total of 10 restricted-range species (eight extant, one now extinct on Hawai'i, one globally extinct) are shared solely with the Central Hawaiian Islands (EBA 217), but 16 (seven extant, nine globally extinct) are endemic, making Hawai'i an EBA in its own right.

The three separate island populations of Chasiempsis sandwichensis differ strikingly in plumage coloration and may prove to be separate species; three subspecies are distinguishable on Hawai'i alone (Pratt 1980, 1993). Hawaiian Stilt Himantopus mexicanus knudseni is also sometimes recognized as a separate species.

This EBA has suffered nine extinctions of endemic species in historic times-more than any other EBA-and many more taxa had become extinct through the actions of Polynesian man before the arrival of European explorers in 1778 (Olson and James 1982).

The demise of the avifauna can be attributed to: forest clearance and degradation for agriculture and forest products (especially in the lowlands; there are now extensive man-made grasslands on the island's drier leeward side); hunting by early settlers; introduced predators; introduced browsers (pigs, goats, sheep, cattle) and plants leading to habitat deterioration; competition from introduced birds; and diseases, especially those carried by introduced mosquitoes (see EBA 217 for more detail).

There are also a number of recently emerging land uses dependent on new technologies (e.g. wood-chipping, geothermal energy, astronomical research) and additional indirect impacts derived from tourist-related, coastal economic development (Juvik et al. 1992). Nevertheless, the threatened endemic species are in general less critically imperiled than those of the Central Hawaiian Islands (EBA 217) because they enjoy more extensive tracts of high-elevation habitat (Pratt 1993).

However, the survival of Branta sandvicensis (the state bird) is dependent on releases of captive-bred stock (c.2,100 birds in total during 1960-1990) to maintain numbers-a population of 339 birds on Hawai-i in 1989-1990. Problems identified specifically for this species include inbreeding depression, loss of adaptive skills, disease, poaching, road kills, dietary deficiencies and predation by introduced mammals (Black et al. 1991, Marshall and Black 1992).

The endemic Corvus hawaiiensis, a primarily fruit-eating, forest-inhabiting crow, is now found only in central Kona (believed to be restricted to one privately-owned ranch) as a result of commercial logging, conversion of forest to agriculture and ranching, and shooting. In 1994 it numbered 31-36 birds in both wild and captive flocks and is the subject of a captive-breeding and release programme (National Research Council 1992).

As well as its nine threatened restricted-range species, three subspecies (important because of potential taxonomic changes; see 'Restricted-range species', above) also qualify as threatened: Mauna Kea 'Elepaio Chasiempis sandwichensis bryani, Kona 'Elepaio C. s. sandwichensis and Himantopus mexicanus knudseni (H. D. Pratt in litt. 1994).

Some 10% of Hawai'i is currently included in protected areas, the Hawai'i Volcanoes National Park being world famous (though not established for its biological features, it has recently been expanded to include more forest). However, some important forested areas are still unprotected, notably those of central Kona.

A detailed survey of Hawaiian forest birds (Scott et al. 1986) has shown that the native avifauna is most intact in four refugia: the mamane'naio woodlands around Mauna Kea, the ohia forest on the windward Hamakua coast (Hakalau National Wildlife Refuge, recently established there as a consequence of these surveys, houses most rare species and is therefore extremely important: S. L. Pimm in litt. 1996), the Kau forest (koa'ohia and ohia forest on the south-east slopes of Mauna Loa), and forests on the north slopes of Hualalai. Conservation priorities include securing ownership or management agreements for several important forest areas, removing feral ungulates and pigs, and controlling introduced plants in essential habitat.

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Hawai'i. Downloaded from https://datazone.birdlife.org/eba/factsheet/212 on 23/11/2024.