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Site description (2011 baseline):
Site location and context
The Kona Forests Important Bird Area is located on the island of Hawai`i and encompasses the western flank of Mauna Loa Volcano and lands surrounding Hualalai Volcano. Both these volcanoes are active, though Hualalai has not erupted since 1801. The IBA includes about 65,265 hectares from near sea level to just over 7,000 feet (2,130 meters) elevation. Land parcels within the IBA include the Kona Forest National Wildlife Refuge, Pu`u Wa`a Wa`a State Forest Bird Sanctuary, Manuka and Kipahoehoe State Natural Area Reserves, Pu`u Wa`a Wa`a, South Kona, Honualoa, and Waiaha Springs State Forest Reserves, unencumbered State lands, The Nature Conservancy's Kona Hema Preserve, and numerous private parcels. The terrain consists of gentle to moderate slopes, punctuated in some areas by volcanic craters and vents. Areas of older lava are densely vegetated, but many recent, barren lava flows cross the area. The Kona area is in the rain shadow of Mauna Loa and Mauna Kea, and the dominant habitat types are dry and mesic forest. Annual rainfall ranges from one to two meters, peaking around 600-900 meters (2,000-3,000 feet) elevation. Habitat loss and disturbance has been extensive in Kona, from cattle ranching, timber harvesting, and urban and agricultural development. There are fairly large contiguous tracts of forest remaining in south Kona and a moderately-sized section on the northern slope of Hualalai, but elsewhere the native forest habitat has been severely fragmented. The forest is patchy and has little understory in some parts of the IBA, but the potential for forest restoration is good. Native plants dominate some areas, but alien plants are widespread, particularly at lower elevations. The upper (eastern) boundary of the IBA follows the 7,000-foot (2,130-meter) contour in some areas, because land above this is mostly sparse shrubland and barren lava, but in many areas the upper boundary is lower because of forest clearing.
The Kona Forests Important Bird Area supports relatively large and important populations of several endemic Hawaiian birds. The endangered `Io or Hawaiian Hawk (Buteo solitarius) is found only on the island of Hawai`i and is particularly numerous in the Kona region. The `I`iwi (Vestiaria coccinea) and `Elepaio (Chasiempis sandwichensis), both species of global conservation concern, are widespread but may be declining. The `Apapane (Himatione sanguinea) and Common (Hawai`i) `Amakihi (Hemignathus virens) are the most abundant native birds in the IBA and also occur on other islands, but still have globally restricted ranges, and the Kona area supports large and important populations. Two forest birds that are endemic to Hawai`i Island and listed under the U.S. Endangered Species Act, the Hawai`i Creeper (Oreomystis mana) and Hawai`i `Akepa (Loxops coccineus) occur in the Kona area in small numbers, primarily on the Kona Forest National Wildlife Refuge and adjacent lands. The population of Nene or Hawaiian Goose (Branta sandvicensis) on the island has been augmented with captive bred birds, and about 97 Nene now use the Kona area, mostly in north Kona on the slopes of Hualalai. Small numbers of the Hawaiian Petrel (Pterodroma sandwichensis), another endangered species endemic to the Hawaiian Islands, are known to transit the area while commuting to nesting areas higher on Mauna Loa, and it is possible that a few petrels nest along the top margin of the IBA. The last wild `Alala or Hawaiian Crow were observed in June 2002 on the Kona Forest National Wildlife Refuge and adjacent private lands. A captive breeding program has been established for the `Alala, and some of the best potential reintroduction sites are in the Kona Forest IBA.
The Kona Forests Important Bird Area is located between sea level and 7,000 feet (2,130 meters) elevation on the western side of the island of Hawai`i. The terrain in this area consists of gentle to moderate slopes, punctuated in some areas by volcanic craters and vents. The distribution of habitats is determined by age and chemical composition of the lava substrate, elevation, and rainfall. Recent lava flows downslope from active volcanic vents are covered by barren lava that is slowly colonized by pioneer species such as `ohi`a (Metrosideros polymorpha), `ohelo (Vaccinium spp.), and a variety of ferns. Gradual weathering of lava produces soil that allows establishment of more diverse and complex plant communities. Rainfall is low throughout the area due to the rain shadows of Mauna Loa and Mauna Kea to the east, ranging from one to two meters per year and peaking around 600-900 meters (2,000-3,000 feet) elevation. Rainwater percolates rapidly into the porous volcanic rock and soil and there are virtually no permanently flowing streams. `Ohi`a and koa (Acacia koa) are the dominant canopy trees, and other common tree include `olapa (Cheirodendron trigynum), kolea (Myrsine lessertiana), pilo (Coprosma spp.), tree ferns (Cibotium spp.), and a variety of non-native plants such as strawberry guava (Psidium cattleianum). At higher elevations the forest becomes more open and sparse, where mamane (Sophora chrysopylla) is more common, eventually giving way to subalpine shrubland dominated by `a`ali`i (Dodonaea viscosa), pukiawe (Leptecophylla tameiameiae), and `ohelo.
Much of the land comprising the Kona Forests Important Bird Area is used for conservation purposes, but some privately owned parcels are used for cattle ranching, agricultural crops such as coffee and macadamia nuts, and harvesting of koa trees for timber. There is very little public access throughout the area. Entry into the Kona Forest National Wildlife Refuge, Pu`u Wa`a Wa`a State Forest Bird Sanctuary, Manuka and Kipahoehoe State Natural Area Reserves, and Kona Hema Nature Conservancy Preserve is restricted by permit only to protect delicate natural ecosystems and prevent the spread of invasive species. The state forest reserves are used for conservation in addition to other purposes, such as public hunting of alien ungulates. Manuka State Wayside Park contains picnic facilities and a short nature trail.
Pressure/threats to key biodiversity
The greatest threats to birds in the Kona Forests IBA are diseases carried by alien mosquitoes, invasive alien plants, alien ungulates, predation by alien mammals, logging, and urban and agricultural development. Abundance of endemic forest birds is higher above 1,500 meters elevation because the parasite that causes avian malaria and the alien mosquito that carries malaria and avian pox cannot tolerate cold temperatures. `Akiapola`au, Hawaii Creeper, and `Akepa occur only above 1,500 meters. Nectarivorous `I`iwi and `Apapane move altitudinally in search of flowering trees and can be exposed to diseases when they descend. Global warming may allow mosquitoes to increase in range, reducing the amount of disease-free habitat. Feral sheep and cattle browse native plants and prevent forest regeneration. Feral pigs degrade native forest by uprooting understory plants, preventing regeneration of native trees, spreading the seeds of invasive alien plants, and creating wallows where mosquitoes breed. Hollowed trunks of tree ferns toppled by feral pigs are the primary breeding site for mosquitoes in some areas. 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 strawberry guava and christmasberry. Black rats are the most serious predator on nests of many forest birds. Mongoose (Herpestes auropunctatus) and feral cats are the most serious predators on ground-nesting Nene and Hawaiian Petrels. Koa trees are logged on some private lands. A few parcels are fenced against ungulates, including Pu`u Wa`a Wa`a State Forest Bird Sanctuary and Kona Hema Nature Conservancy Preserve, and there are several smaller exclosures to protect individual rare plants. Active forest restoration is occurring in some areas such as Kona Hema Nature Conservancy Preserve.
Lands comprising the Kona Forests Important Bird Area are owned by several different government agencies and private groups. The State of Hawai`i owns the largest proportion of the IBA overall (59%). Land parcels within the IBA include the Kona Forest National Wildlife Refuge (3%), Pu`u Wa`a Wa`a State Forest Bird Sanctuary (2%), Manuka and Kipahoehoe State Natural Area Reserves (19%), Pu`u Wa`a Wa`a, South Kona, Honualoa, and Waiaha Springs State Forest Reserves (36%), unencumbered State lands (2%), The Nature Conservancy's Kona Hema Preserve (5%), and numerous large and small private parcels (33%). Private lands are owned by Kamehameha Schools, Yee Hop Ranch, E. Stack. T. Atwood, S. Rolles Trust, One Keahole, and several other smaller landowners.
Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Kona Forests (USA). Downloaded from
https://datazone.birdlife.org/site/factsheet/kona-forests-iba-usa on 23/11/2024.
