Mauna Kea Mamane - Naio Forest

Country/territory: USA

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

Area: 21,142 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 not assessed
For more information about IBA monitoring please click here

Site description
The mamane-naio ecosystem is a dry, high elevation forest and shrubland that occurs in a ring around Mauna Kea Volcano from approximately 2000 meters elevation to treeline at 2850 meters (6,600 to 9,400 feet). It is dominated by two tree species, mamane (Sophora chrysophylla) and naio (Myoporum sandwicense). This habitat type has been severely impacted throughout Hawaii by cattle ranching, browsing by feral sheep and goats, and fires. Mauna Kea supports the best remaining example of this habitat type, and the largest area of intact mamane-naio forest occurs on the southwestern slope of Mauna Kea near Puu Laau. The area is characterized by steadily sloping terrain that is punctuated by steep volcanic cinder cones. The soil is cinder or loosely compacted volcanic ash. The forest is fairly low in stature, with the largest trees only 10-12 meters tall. Trees grow slowly in this cold, dry environment. Large mamane trees often have a twisted, ancient-looking growth form, and even small trees may be quite old. The forest becomes more stunted at higher elevations, eventually giving way to montane shrubland and then bare ash, cinder, and rock toward the 13,796 foot summit of Mauna Kea. Rainfall is low, less than 400 mm (15.7 in) per year over the western slope, but clouds and mist roll up from the lowlands on many afternoons, providing another source of moisture. Rainwater runs off or percolates rapidly due to the steep terrain and porous volcanic soil. Freezing temperatures occur on many nights, especially during the winter months, but snow is infrequent and occurs only at the upper limit of the habitat in association with winter storms. Mamane-naio forest also occurs at similar elevations on Mauna Loa and Hualalai and formerly occurred at lower elevations, but it has been more severely degraded in those areas, and on Mauna Loa it does not extend as high in elevation due to more recent volcanic activity.

Key biodiversity
The mamane-naio forest on Mauna Kea contains the entire world population of Palila (Loxioides bailleui), a Hawaiian honeycreeper endemic to the island of Hawaii, and the last finch-billed honeycreeper in the main islands. Adult Palila feed almost exclusively on mamane seed pods and also nest primarily in mamane. Roughly 96% of the Palila population occurs on the southwestern slope of Mauna Kea where the widest and most intact belt of mamane forest exists. A few Palila occur in remnant forest on the southern slope of Mauna Kea, and a few were found near Puu Kanakaleonui on the eastern side of Mauna Kea, but none have been observed there for several years. A combination of translocations and releases of captive-bred birds has resulted in establishment of a small Palila population in a mamane-naio forest remnant on the northern slope of Mauna Kea near Puu Mali. The population of Palila at Puu Mali is still very small (less then 20 birds), but in 2006 there were several successful nests. The mamane-naio forest also supports populations of several other endemic birds. Common (Hawaii) Amakihi (Hemignathus virens) are particularly abundant and reach some of their highest known densities, up to 940 birds per square kilometer. Apapane (Himatione sanguinea) and Iiwi (Vestiaria coccinea) are less common but substantial numbers of these nectarivorous species may visit seasonally from lower elevations when mamane flowers are in bloom. This dry forest supports an isolated population of Elepaio that is currently regarded as a distinct subspecies (Chasiempis sandwichensis bryani) and is found only in this area. The Pueo or Hawaiian Short-eared Owl (Asio flammeus sandwichensis) is commonly observed hunting over the mamane forest and adjacent grassland. The Io or Hawaiian Hawk (Buteo solitarius) is rarely seen in this area. Small numbers of Akiapolaau formerly occurred in the mamane forest, particularly at Kanakaleonui, but they are now rarely observed.

Recommended citation
BirdLife International (2022) Important Bird Areas factsheet: Mauna Kea Mamane - Naio Forest. Downloaded from http://www.birdlife.org on 07/12/2022.