Bokak Atoll (23787)
Marshall Islands, Oceania
Site overview
KBA status: confirmed
Global KBA criteria: D1a
Year of last assessment: 2012
National site name: Bokak Atoll
Central coordinates: Latitude: 14.5875, Longitude: 168.9890
System: marine, terrestrial
Elevation (m): 0 to 5
Area of KBA (km2): 4.84445
KBA classification: Global
Legacy site: Yes
Site details
Site description: Bokak (Taongi) is an uninhabited atoll, the northernmost and most isolated in the Marshall Islands. It is low and dry, semi-desert and very stony. Ten islets form the atoll. The atoll is home to congregations of breeding seabirds and a rare semi-arid atoll ecosystem.
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.
Additional biodiversity: The entire atoll of Bokak (Bakak, Pakak, Taongi) in the Ratik chain is proposed as an IBA under the A4 criteria (Figure 5). Bokak has consistently shown records of thousands of birds (Fosberg, 1955; Amerson, 1969; Thomas, 1989). Using only the minimum populations recorded (which may have been taken during a non-nesting period), the atoll was still shown to have around 36,750 individual birds, meeting several of the A4 criteria. Bokak meets the A4i criteria, for >1% of the regional biogeographic population for Sooty Terns. The 1% regional biogeographic threshold is 20,000 individuals (Appendix 1). Amerson (1969) reported as many as 20,000 Sooty Terns for the atoll. Bokak meets the A4ii criteria for >1% of the global population for Red-footed Boobies and Great Frigatebirds. The 1% global threshold for Red-footed Boobies is 1,500 pairs, which this report has converted to 3,000 individuals. The recorded populations of Red-footed Boobies ranged from 3,500 to 4,500 individuals, exceeding the threshold. The 1% global threshold for Great Frigatebirds is 850 pairs, which this report converted to 1,700 individuals. The recorded populations of Great Frigatebirds ranged from 5,300 to 7,300, exceeding this threshold. The A4iii criteria requires >20,000 waterbirds or seabirds. At a minimum, the population was 36,750 individual birds, exceeding this threshold. Non-bird biodiversity: Bokak, together with Bikar, are possibly the only remaining examples in the world of unaltered semi-arid atoll ecosystems. Bokak is also home to a confirmed endemic grass, Lepturus gassparicensis, and to nesting Green Sea Turtles (NBT, 2000). While the atoll has only nine species of flowering plants, all nine are native and the vegetation is completely undisturbed by exotics (Thomas, 1989). The atoll provides the best remaining examples of Scaevola sericea and Sida fallax shrubland in the RMI.
Delineation rationale: Whole atoll, comprising 10 motu. 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 246 ha (Global Islands Database) to 484 ha (GIS).
Habitats
Summary of habitats in KBA: Bokak atoll is low and dry, semi-desert and very stony.
| IUCN Habitat | Coverage % | Habitat detail |
|---|---|---|
| Marine Intertidal | 20 | |
| Desert | 20 | |
| Marine Coastal/Supratidal | 20 | |
| Shrubland | 20 | |
| Marine Neritic | 20 |
Threats
Summary of threats to biodiversity at KBA: Rats and the potential spread of invasive species pose the greatest threat. Bokak atoll is described as the least disturbed atoll in the RMI (NBT, 2007), although there is confirmed presence of rats (Thomas, 1989). Both Bokak and Bikar are outlying atolls and difficult to access. Bikar similarly has confirmed presence of rats (Thomas, 1989). Taka atoll’s proximity to the habited atoll of Utirik has allowed for access and use of the atoll by nearby residents. Thomas (1989) describes residents from Utirik harvesting birds, fish, turtles, and clams from Taka several times a year.
| Threat level 1 | Threat level 2 | Threat level 3 | Timing |
|---|---|---|---|
| Invasive & other problematic species, genes & diseases | Invasive non-native/alien species/diseases | Named species | Ongoing |