Niuafo'ou (24503)
Tonga, Oceania
Site overview
KBA status: confirmed
Global KBA criteria: A1a, B1, B2
Year of last assessment: 2007
National site name: Niuafo'ou
Central coordinates: Latitude: -15.6000, Longitude: -175.6333
System: marine, terrestrial
Elevation (m): 0 to 260
Area of KBA (km2): 53.02341
KBA classification: Global
Legacy site: Yes
Site details
Site description: Niuafo’ou IBA comprises the whole island of Niuafo’ou which until recently supported the only extant population of the Tongan megapode Megapodius pritchardii. The island is an active volcano and the megapodes lay their eggs in soil heated by volcanic ducts. An island-endemic form of the Polynesian Starling Aplonis tabuensis nesiotes occurs on the island, along with two other range restricted species, the Crimson-crowned Fruit-dove Ptilinopus porphyraceus and the Blue-crowned Lorikeet Vini australis.
Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance that meets the thresholds for at least one criterion described in the Global Standard for the Identification of KBAs. KBA identified in the CEPF Ecosystem Profile of the Polynesia-Micronesia Hotspot (2007). Taxonomy, nomenclature and threat status follow the 2003 IUCN Red List.
Additional biodiversity: Seventeen bird species have been recorded breeding on Niuafo’ou (Goth & Vogel 2001; Rinke 1986,1991). Niuafo'ou is best known for the Tongan megapode Megapodius pritchardii, the only surviving megapode east of Vanuatu. Megapodes were probably common throughout Fiji, Tonga and Samoa but were one of the first species to succumb to the arrival of the first people. The Tongan megapode is thus of considerable national and international significance. Megapodes have the unique behaviour of laying their eggs in unconsolidated soils or organic debris, allowing external heat sources to provide for incubation without any parental care. On Niuafo'ou the Tongan megapode seek out well established `breeding grounds' where the soil is heated by volcanic ducts. Sixteen of these sites are known but those outside the crater are no longer used because of continued removal of the eggs by the islanders. Other unknown and inaccessible sites may also occur. The current population of the Tongan megapode on Niuafo’ou is estimated to be 188-235 pairs Goth & Vogel 1995), but it is a shy and rarely seen species (Rinke 1991). There is only one native passerine on Niuafo’ou, an endemic form of the Polynesian starling Aplonis tabuensis nesiotes. This and the Blue-crowned Lory Vini australis are two central Polynesian restricted range species which occur on the island, the former is abundant and the latter common . Two feral species introduced to Fiji have also arrived naturally or been boat-assisted to Niuafo'ou, the red-vented bulbul Pycnonotus cafer and the jungle mynah Acridotheres fuscus. Two seabirds, tropical shearwater Puffinus bailloni (previously Audubon’s shearwater P.lherminieri) and the white-tailed tropic bird Phaethon lepturus breed on Niuafo'ou, whereas the wedge-tailed shearwater P. pacificus is collected in large numbers on the island, but there is no evidence of breeding (Goth & Vogel 1995). Non-bird biodiversity: Niuafo’ou’s biodiversity has not been well studied. There is no plant list for the island but there are no known endemic species (Whistler pers.comm. Oct.1994). Within Tonga, Niuafo'ou is well known for the fine Ta'ovala weaved from the inner bark of the Fanakio tree, Sterculia fanahio which is widely regarded to occur only on Niuafo'ou. This is true in respect of Tonga, but it is also found in Samoa, Rotuma and Niue. It is widespread on the island and will remain so as long as fruiting trees survive and the Pacific pigeon Ducula pacifica survives in numbers to distribute its seeds. Seven skinks and two geckos have been recorded on Niuafo'ou . None of these are island or Tongan endemic species but two of them Emoia nigra and E.adspersa are not found south of the Niuas (Prescott & Folaumoetu’I 2004).
Delineation rationale: 2012-12-17 (BL Secretariat): original polygon clipped to hi-res coastline following identification in October 2012 of new marine IBA offshore this site; site area consequently changed from 5800 ha to 5302 ha. 2015-10-20 (BL Secretariat): IBA includes the KBA 'Niuafou Freshwater Lake' (CEPF Ecosystem Profile 2007).
Habitats
Summary of habitats in KBA: Niuafo'ou is the Kingdom of Tonga's most remote island and at 640 km north of Tongatapu it is closer to Fiji and Samoa. The 8-km-wide circular island forms the summit of a largely submerged basaltic shield volcano. The island encloses a 5-km-wide caldera that is mostly filled by a lake whose bottom extends to below sea level. The inner walls of the caldera drop sharply to the caldera lake, Vai Lahi, which contains several small islands and pyroclastic cones on its north east shore. Niuafo'ou is an active volcano and there have been 11 eruptions since 1814, the last major eruption being in 1946 after which the inhabitants were evacuated to 'Eua. Some of the former residents returned in 1958 and today the population has risen to approximately 800 living in about 140 households in eight villages. Much of Niuafo'ou is barren lava flow. Approximately one third of the land area has potential for agriculture, and two soil types are currently recognised, a clay with good agricultural potential which covers slightly more than half of the arable land and a sandy loam, with lesser potential, which covers the remainder. Most of the accessible arable areas have or are planted on an extensive basis to yams, cassava, taro, bananas, plantains and vegetables. The only commercial crop that has been planted is copra. Undisturbed dense, humid broad-leaved forest is only found on the inner walls of the crater lake and its islands, while the island's outer slopes comprise a mosaic of regenerating forest, agricultural gardens and lava flows of varying antiquity. The majority of agricultural areas are on the north and eastern slopes, while the southern and western slopes are relatively barren.
| IUCN Habitat | Coverage % | Habitat detail |
|---|---|---|
| Rocky Areas(e.g., inland cliffs, mountain peaks) | 25 | |
| Marine Coastal/Supratidal | 35 | |
| Forest | 10 | |
| Artificial - Terrestrial | 30 |
Threats
Summary of threats to biodiversity at KBA: It is probable that all nesting sites on Niuafo'ou are known to villagers and are harvested, and at least 50% of all eggs laid are collected or destroyed (Goth & Vogel 1995). Adults are also hunted on a small scale, and adults and chicks are predated by feral cats and dogs, while pigs may compete for food. Fonualei is uninhabited so the threats of hunting and human disturbance are less immediate for the population there, however, Founalei is small and an active volcano, a major eruption could see the demise of the entire population.
| Threat level 1 | Threat level 2 | Threat level 3 | Timing |
|---|---|---|---|
| Biological resource use | Hunting & collecting terrestrial animals | Intentional use (species being assessed is the target) | Ongoing |
| Invasive & other problematic species, genes & diseases | Invasive non-native/alien species/diseases | Named species | Ongoing |
Additional information
References: Crane, W. 1992. The Environment of Tonga: A Geography Resource. Wendy Crane Books, Lower Hutt. Goth, A. and U. Vogel. 1995. Status of the Polynesian Megapode (Megapodius pritchardii) on Niuafo’ou (Tonga). Bird Conservation International 5:117-128. Goth, A. and U. Vogel. 2001. Notes on breeding and the conservation of birds on Niuafo’ou Island, Kingdom of Tonga. Pacific Conservation Biology 5: 103-114. Jenkins, J.A.F. 1980. Seabird records from Tonga-an account based on the literature and recent observations. Notornis 27:205-235. Prescott, N. and P. S. Folaumoetu’I (Editors). 2004. Tonga Biodiversity Stocktaking. Technical Report 1 for the National Biodiversity Strategy and Action Plan. Dept. of Environment, Nuku’alofa Rinke, D. 1986. Notes on the avifauna of Niuafo’ou Island, Kingdom of Tonga. Emu 86:145-151. 1991. Birds of ‘Ata and Late, and additional notes on the avifauna of Niuafo’ou Island, Kingdom of Tonga. Notornis 38: 131-151. Rinke, D., L.H.Soakai and A.Usback. 1993. Koe Malau: Life and future of the Malau. Brehm Fund for International Bird Conservation, Bonn. Stattersfield, A.J., M.J. Crosby, A.J. Long, and D.C. Wege. 1998. Endemic Bird Areas of the World: Priorities for biodiversity conservation. BirdLife Conservation Series no. 7, BirdLife International, Cambridge, UK. 846 pp. Watling, D. 2003. Report on a Visit to Late and Fonualei Islands, Vava'u Group, Kingdom of Tonga. Unpublished Report to the Van Tienhoven Foundation. Watling, D. 2004. Report on a Visit to Late Island, Vava'u Group, Kingdom of Tonga. Unpublished Report to the Van Tienhoven Foundation.