The Kaua`i Forests and Uplands Important Bird Area occupies most of the central and northwestern portions of Kaua`i and contains most of the native forest and intact upland habitats remaining on the island. It is 77,420 hectares (191,227 acres) in size and extends from sea level along the northwestern coastline to the highest summits, Wai`ale`ale at 1569 meters (5148 feet) and Kawaikini at 1598 meters (5243 feet). The core of the area is the broad Alaka`i Plateau that slopes gradually downward from east to west. The terrain is extremely rugged, with deep canyons eroded into the plateau on all sides, including spectacular Waimea and Olokele Canyons on the south and the dramatic Na Pali coastline on the northwest. These canyons contain numerous waterfalls, isolated hanging valleys, and precipitous cliffs over 600 meters (2000 feet) high. Annual rainfall ranges from about one meter (39.3 inches) in the southwest to 11.5 meters (450 inches) near the summit of Wai`ale`ale, one of the wettest spots on earth. Even the relatively flat Alaka`i Plateau is etched with innumerable streams and narrow gulches that make pedestrian access challenging. Much of the area is covered in dense forest and montane shrubland. Bogs with stunted vegetation occupy some depressions in the plateau. The higher elevations contain some of the most intact native ecosystems in Hawai`i, but invasive alien plants dominate much of the lowlands. The area includes the State Alaka`i Wilderness Preserve, the State Hono `O Na Pali and Kuia Natural Area Reserves, all or part of the Halelea, Moloa`a, Na Pali-Kona, Kealia, Pu`u Ka Pele, and Lihue-Koloa State Forest Reserves, Koke`e, Waimea Canyon, Haena, Na Pali Coast, and Polihale State Parks, Wailua, Kekaha, and Mokihana State Game Management Areas, and The Nature Conservancy?s Kana`ele Preserve.
The Kaua`i Forests and Uplands IBA supports one of the greatest concentrations of endemic Hawaiian forest birds, including the entire population of several species that are endangered or of global conservation concern. The endangered Puaiohi numbers about 400 birds and nests only on cliffs along narrow streams where it is safe from predators. The `Akikiki or Kaua`i Creeper and the `Akeke`e or Kaua`i `Akepa number about 1,312 and 3,536 individuals, respectively. Both are declining and were recently petitioned for listing. The Kaua`i `Amakihi and `Anianiau are more numerous at about 40,000 individuals each, but are restricted to Kaua`i and are species of global conservation concern. `I`iwi and `Elepaio occur on other islands but are somewhat less numerous at about 10,000 and 23,000 individuals and are also species of global concern. The remote forests of the upper `Alaka`i are the last possible refuge for several extremely rare endemic birds, the Kama`o, Kaua`i `O`o, Nukupu`u, and `O`u. These species have not been observed for 10-20 years and may be extinct, but if they still survive it is somewhere in the Kaua`i Forests and Uplands IBA. Their status cannot be known with certainty until the most remote areas of Kaua`i have been adequately searched.
The remote mountains and steep slopes of Kaua`i provide vital breeding sites for several seabirds, including threatened Newell?s Shearwater, endangered Hawaiian Petrel, which are endemic to the Hawaiian Islands, Band-rumped Storm-petrel, which is a candidate for listing, and White-tailed Tropicbird. The number of birds is difficult to estimate and the location of most colonies is unknown, but populations have declined recently and some former colonies have been extirpated. Kauai`i supports the vast majority of nesting Newell?s Shearwaters. The endangered Nene or Hawaiian Goose was reintroduced to Kaua`i in 1985, and one population of about 80 individuals uses the northwestern edge of the area along the Na Pali coast.
The greatest threats to forest birds on Kaua`i are diseases carried by alien mosquitoes, invasive alien plants, alien ungulates, and predation by alien mammals. The parasite that causes avian malaria and the mosquito that carries malaria and avian pox virus cannot tolerate cold temperatures, so most forest birds are restricted to the highest, coldest parts of the island above about 1,500 meters (4,000 feet). The amount of disease-free habitat on Kaua`i is small and may diminish if global warming allows mosquitoes to invade the highest areas that once provided thermal refuge from disease. Invasive alien plants displace native plants needed by forest birds for nesting and foraging and often grow in monocultures that reduce floristic diversity. Some of the worst invasive plants are ginger, strawberry guava, and black wattle. Feral pigs degrade native forest habitat by uprooting understory plants, preventing regeneration of native trees, spreading the seeds of invasive alien plants, and creating wallows where mosquitoes breed. Feral goats are a problem primarily in drier areas by browsing native vegetation and increasing erosion. Black rats are the most serious predator on nests of many forest birds, and feral cats are the most serious predator on ground-nesting birds like Nene and seabirds. Mongoose are not established on Kaua`i, but their arrival would be devastating for all ground-nesting birds. For Hawaiian Petrels and Newell?s Shearwaters the greatest threats are predation by feral cats, rats, and alien Barn Owls, attraction to artificial lights, collisions with man-made structures such as towers and utility lines, and invasive alien plants that alter vegetation structure and allow predators to access nests. Fledgling Newell?s Shearwaters are particularly vulnerable to light attraction and collisions, hundreds are picked up along roadways and urban areas every year as part of the ?Save Our Shearwaters? program.
The majority of lands comprising the Kaua`i Forests and Uplands IBA are owned by the State of Hawai`i (62%), with the remainder being privately owned lands that are administered by the State of Hawai`i as forest reserves (38%), and less than 1% owned by The Nature Conservancy of Hawai`i. State lands include the Alaka`i Wilderness Preserve (6%), the Hono O Na Pali and Kuia Natural Area Reserves (2%), all or parts of the Halelea, Moloa`a, Na Pali-Kona, Kealia, Pu`u Ka Pele, and Lihue-Koloa State Forest Reserves (36%), Koke`e, Waimea Canyon, Haena, Na Pali Coast, and Polihale State Parks (7%), and the Wailua, Kekaha, and Mokihana State Game Management Areas (11%).
The Kaua`i Forests and Uplands IBA contains a variety of habitats and their distribution is influenced by elevation, rainfall, and degree of human disturbance. Rainfall generated by northeasterly tradewinds causes the northern and eastern slopes to be wetter than the leeward slopes. Rainfall increases with elevation due to adiabatic cooling and condensation that occurs as air is forced upward over the mountain slopes. Annual rainfall ranges from about one meter (39 inches) in lowland leeward areas, to over 11.5 meters (450 inches) near the summit of Wai`ale`ale. Leeward areas support dry forest and shrubland at lower elevations, which grades into mesic forest at middle elevations, and eventually montane rainforest. The wetter windward slopes support mesic or wet forest in the lowlands, which transitions rapidly to rainforest at higher elevations. Depressions and flat areas of the Alaka`i Plateau harbor montane bogs with stunted vegetation and many rare plant species. The windswept, rain-soaked summits and ridges are cloaked in wet moorlands and shrublands. Numerous cliffs and waterfalls provide and additional habitat type and also a refuge for many rare plant species from browsing by alien ungulates. Habitat in much of the lowlands has been substantially modified by invasive alien plants, but much of the upper Alaka`i Plateau and many higher slopes and ridges support largely intact native plant communities. Forested habitats sustained some damage during hurricanes in 1981 and 1992.
Almost all of the land comprising the Kaua`i Forests and Uplands IBA is zoned for conservation and used for some sort of conservation or wildlife-related purpose. The specific uses vary among different parcels. The Alaka`i Wilderness Area is designated for strict conservation purposes. Day hiking is allowed but overnight camping and helicopter access are by permit only. The natural area reserves are also designated for strict conservation purposes. Public hunting of non-native ungulates, primarily feral pigs, is permitted throughout the area, including the wilderness area, all forest reserves, state parks, natural area reserves, and game management areas, but most hunting occurs in the more accessible sections. Public hiking trails are present in much of the area, several picnic areas and camp sites are present in the state parks, and there are many additional unofficial trails. Birdwatching and photography are also popular activities.