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Location Pitcairn Islands (to UK)
Central coordinates 130o 45.00' West  23o 56.00' South
IBA criteria A1, A4i, A4ii, A4iii
Area 1,577 ha
Altitude 0 - 4m
Year of IBA assessment 2005





Site description Oeno is a low oceanic atoll to the North of Pitcairn. The fringing reef is approximately circular and about 4 km in diameter. It is breached by a single passage, on the northern margin. Through this passage, shallow-draft boats (e.g. the Pitcairners' longboats) may enter the lagoon, which is uniformly shallow, less than 3 m deep, with scattered reefs. There is a single motu, about 80 ha in extent, south-west of the centre of the lagoon. North of the motu and intermittently connected to it, a sandspit runs towards the reef.Oeno is a remarkably undisturbed atoll. The margin comprises either sandy beach or reef flat. Behind this lies shoreline scrub, often dominated by Suriana maritima. At the south end of the motu is closed forest of Argusia argentea and Pisonia grandis, the canopy reaching 7-9 m. Most of the rest of motu is clothed in more or less open Argusia scrub. In total there are only 16 vascular plant species present, but this includes the endemic Bidens hendersonensis var. oenoensis. There is also a stand of coconut trees, introduced by the Pitcairners, at the north of the island.Because the entrance to the lagoon is too shallow to allow the passage of ocean-going yachts and because there is no secure anchorage outside the reef, Oeno is rarely visited. Once or twice a year, the Pitcairners visit the island to camp in the vicinity of the coconut grove. The visits, typically in the southern summer, normally last around a week and are viewed as holidays.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Phoenix Petrel Pterodroma alba breeding  1991  12,500 breeding pairs  good  A1, A4ii  Endangered 
Murphy's Petrel Pterodroma ultima breeding  2005  1,220 individuals  unknown  A1  Near Threatened 
Red-tailed Tropicbird Phaethon rubricauda breeding  1991  500-1,000 breeding pairs  good  A4ii  Least Concern 
Bristle-thighed Curlew Numenius tahitiensis winter  2005  100 individuals  good  A1, A4i  Vulnerable 
A4iii Species group - seabirds breeding  1991  13,720 breeding pairs  medium  A4iii   

Habitats

IUCN habitat Habitat detail Extent (% of site)
Sea Shallow marine areas, coral reefs and keys  major

Other biodiversity The flora of Oeno is poor in species. Only the local variety of Bidens hendersonensis is endemic; this was not seen in 1991/92, but was relocated in 1997. On the other hand, the marine mollusc fauna is much richer. Around 240 taxa are known, of which about two percent are endemic to the Pitcairn group. One species, a liotinine gastropod, belongs to a genus (and therefore species) known only from Oeno.

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Recommended citation  BirdLife International (2014) Important Bird Areas factsheet: Oeno Island. Downloaded from http://www.birdlife.org on 30/10/2014

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