The Moloka`i Forests Important Bird Area contains most of the native forest remaining on the island. It is 12,295 hectares in size, and extends from near sea level in several locations on the northern shore of the island to the highest summits on the island, Kamakou at 1514 meters (4970 feet) and Olokui at 1404 meters (4606 feet). The terrain is extremely rugged, with narrow ridges separated by deep stream valleys. Sea cliffs over 600 meters (2000 feet) tall, some of the highest in the world, occur in several locations along the northern coastline. Annual rainfall ranges from about one meter in the southwestern part of the area to over four meters at the head of Wailau Valley east of Olokui. Much of the area is covered in dense forest. Invasive alien plants dominate much of the lowlands, but the higher elevations contain primarily intact native forest and shrubland. The Olokui Plateau is an isolated mountain with steep sides that restrict access to alien ungulates, and is one of the most pristine areas in Hawai`i. Despite the high quality native forests that occur in parts of the area, only a few native bird species are left on Moloka`i due to the high prevalence of diseases carried by alien mosquitoes. The area includes the upper elevations of Kalaupapa National Historical Park, Olokui and Pu`u Ali`i State Natural Area Reserves, most of the Moloka`i State Forest Reserve, Kamakou and Pelekunu Nature Conservancy Preserves, and a small amount of private land.
The Molokai Forests Important Bird Area is the last possible refuge for two extremely rare endemic forest birds, the Oloma`o (Myadestes lanaiensis) and the Kakawahie or Moloka`i Creeper (Paroreomyza flammea). Both of these species may be extinct, but if they still survive it is somewhere within the Molokai Forests IBA. Their status cannot be known with certainty until the most remote areas of Moloka`i have been adequately searched, particularly the Olokui Plateau. The Oloma`o has not been observed since 1988 and the Kakawahie has not been observed since 1963 (USFWS 2006). The Oloma`o formerly occurred on Lana`i but is extinct there. A small number of `I`iwi, a species of global conservation concern, persist in forests at the highest elevations on the Olokui Plateau Natural Area Reserve and the Kamakou Nature Conservancy Preserve. `Apapane (Himatione sanguinea) and Hawai`i `Amakihi (Hemignathus virens wilsoni) are fairly common and widespread in many forested areas, even reaching into the lowlands in some locations, though these species have global distributions restricted to the Hawaiian Islands. A small population of the endangered Nene or Hawaiian Goose (Branta sandvicensis) has been reintroduced to the island through release of captive-bred birds at lower elevations on the eastern end of the island that are outside the IBA. Though still small, this population is thriving and appears to be increasing in number and distribution and may soon expand into the Molokai Forests IBA. Hawaiian Petrels (Pterodroma sandwichensis), an endangered species endemic to the Hawaiian islands, have been heard on Moloka`i and are thought to nest there, though the number of birds and location of nesting colonies are unknown.
The greatest threat to forest birds on Moloka`i is disease carried by alien mosquitoes, particularly avian malaria (Plasmodium relictum) and avian pox virus (Poxvirus avium). The mosquito that carries these diseases and the Plasmodium parasite cannot tolerate cold temperatures at high elevations, but unfortunately only a tiny proportion of Moloka`i is sufficiently high to provide thermal refuge from disease, and these areas are not large enough to support viable populations of sensitive species in the long-term. As a result, only species with greater immunity to disease, the `Apapane and `Amakihi, have persisted in any numbers, while more sensitive species, such as `I`iwi and Kakawahie, are restricted to small areas at the highest elevations, or may have become extinct. There are other serious threats to the forest habitat on Moloka`i, such as alien plants that displace native plants, and feral ungulates. Feral pigs degrade native forest habitat by uprooting understory plants, preventing regeneration of native trees, spreading the seeds of invasive alien plants, and creating breeding habitat for mosquitoes in their wallows. Alien axis deer (Cervus axis) also degrade native forest by browsing, and are able to leap over many existing fences. Access to the remote Olokui Natural Area Reserve is highly restricted in order to reduce the risk of introducing alien species. Other alien mammals threaten birds by preying on adults and nests. Black rats (Rattus rattus) are the most serious predator on nests of many Passerine birds in Hawai`i, the small Indian mongoose (Herpestes auropunctatus) is the most serious predator on ground-nesting birds like Nene and Hawaiian Petrels, and feral cats (Felis domesticus) prey on a variety of birds and occur throughout the island.
The majority of lands comprising the Moloka`i Forests IBA are owned by the State of Hawai`i (69%). These include 90% of the Moloka`i State Forest Reserve, all of the Olokui and Pu`u Ali`i Natural Area Reserves, the portion of Kalaupapa National Historical Park included in the IBA, and a portion (3%) of the Pelekunu Nature Conservancy Preserve. A small portion of the State lands on the southwestern edge of the Moloka`i Forest Reserve are specifically held by the State Department of Hawaiian Homelands. The Nature Conservancy owns 1.5% of the IBA, with their holding comprising 8% of their Pelekunu Preserve. Privately owned parcels comprise 30% of the IBA, including one parcel of the Moloka`i Forest Reserve, the Kamakou Nature Conservancy preserve which is owned by Moloka`i Ranch, and numerous parcels that comprise 89% of the Pelekunu Nature Conservancy Preserve.
Almost all of the Moloka`i Forests IBA is zoned for conservation and managed for conservation purposes. Only a small area in Kalaupapa National Historical Park and several slivers along the southwestern edge of the Moloka`i Forest Reserve totaling less than 100 hectares are zoned for agriculture. Most of the land comprising the Moloka`i IBA consists of conservation reserves managed by a variety of government agencies and organizations, including Kalaupapa National Historical Park (24%), Olokui and Pu`u `Ali`i State Natural Area Reserves (10%), the Moloka`i State Forest Reserve (38%), and Kamakou and Pelekunu Nature Conservancy Preserves (27%), and one small private parcel (<1%). Public hunting of non-native ungulates is permitted in all the State Forest Reserves and Natural Area Reserves, and in the upper elevations of Kalaupapa National Historical Park. A few public hiking trails are present in the area, and there are many additional unofficial trails used primarily for hunting.