Oahu Uplands

Country/territory: USA

IBA Criteria met: A1, A2 (2009)
For more information about IBA criteria please click here

Area: 39,704 ha

Audubon / American Bird Conservancy
Most recent IBA monitoring assessment
Year of assessment Threat score (pressure) Condition score (state) Action score (response)
2009 high not assessed low
For more information about IBA monitoring please click here

Site description
The O`ahu Uplands IBA encompasses most of the remaining native forest on O`ahu. The area is divided between the Ko`olau Mountain Range in the east, which contains 32,828 hectares, and the Wai`anae Mountain Range in the west, which contains 6,875 hectares. The IBA extends from 100 meters (330 feet) elevation in the southern Ko`olaus, to 960 meters (3150 feet) at the summit of Konahuanui in the Ko`olaus and 1220 meters (4003 feet) at the summit of Ka`ala in the Wai`anaes. Some of the area has been disturbed by human development and agriculture, and a variety of alien plants have invaded many areas. Disturbance has been generally more severe at lower elevations and in valleys, but much of the remote central and northern Ko`olau Range consists of largely intact native forest and shrubland. The area is split by several major roads. The terrain is rugged, with steep, narrow ridges separated by deep stream valleys, precipitous cliffs that rise 2000 feet in some areas, and numerous waterfalls. The area ranges from dry on the leeward (western) side of the Wai`anae range, to extremely wet on the summit ridge of the Ko`olaus, where annual rainfall exceeds seven meters (275 inches). Summit areas are often shrouded for days at a time in a dense cloud layer produced by adiabatic cooling of moist air swept upward over the mountains by northeasterly trade winds. Habitats include dry forest and shrubland, mesic forest and woodlands, dense montane rainforest, montane bogs, and wet moorlands with stunted vegetation on windswept ridges. Ownership and use of the land is complex and includes portions of several State Forest Reserves, two State Natural Area Reserves, several State Parks and Recreation Areas, the O`ahu Forest National Wildlife Refuge, Honouliuli Preserve managed by The Nature Conservancy, several large parcels owned or leased to the U.S. military, and various private lands.

Key biodiversity
The O`ahu Uplands IBA contains globally significant populations of several bird species endemic to the Hawaiian Islands. Virtually the entire population of the O`ahu `Amakihi (Hemignathus flavus) occurs within the O`ahu Uplands IBA. `Amakihi are fairly common in the central and southern Ko`olaus and the southern Wai`anaes, but inexplicably rare or absent in extensive tracts of native forest in the northern Ko`olaus and Wai`anaes. `Amakihi have recently increased in some areas, and can even be found in suburban gardens in the foothills behind Honolulu. The O`ahu `Elepaio (Chasiempis ibidis) occurs entirely within the O`ahu Uplands IBA. This species occurs only on O`ahu and is listed as endangered under the U.S. Endangered Species Act, a. It has a highly fragmented range, with six core populations and numerous small population remnants. `Apapane (Himatione sanguinea) are fairly common on the mountain ridges of O`ahu, especially in the Ko`olaus, but have a globally restricted distribution limited to the main Hawaiian Islands. Very small numbers of `I`iwi (Vestiaria coccinea) persist in both the Wai`anae and Ko`olau Ranges. Their numbers are difficult to determine because they are observed infrequently and may move in search of nectar resources. The O`ahu Alauahio or Creeper (Paroreomyza maculata) has not been seen since 1985 and may be extinct, but if it still survives it is somewhere in the O`ahu Uplands. The Pueo or Hawaiian Short-eared Owl (Asio flammeus sandwichensis), a subspecies endemic to the Hawaiian islands, occurs in small numbers in forested areas and adjacent grasslands. Seabird nesting colonies exist in several areas of the O`ahu Uplands. White-tailed Tropicbirds (Phaethon lepturus) nest on cliffs in several valleys, and federally threatened Newell's Shearwaters (Puffinus auricularis newelli) have been heard recently on the slopes above Kalihi Valley.

Recommended citation
BirdLife International (2023) Important Bird Areas factsheet: Oahu Uplands. Downloaded from http://www.birdlife.org on 31/01/2023.