Location: 20.1N, 145.0E
Elevation: 227m (746 ft.)Area 2 sq. km
Island type: 3 islet remnants of volcanic cone, North (227m), East (215m) and West (178m), with steep cliffs of columnar basalt; submerged coral limestone terrace at 25m depth off West Island.
The three small islands are the rim of the submerged summit crater of Maug volcano. The volcano is made of pyroclastic rocks and thin layers of tholeiitic basalt. Submarine domes on the crater floor are the youngest features at Maug. The inner wall of East Island shows a vertical dike seen slicing up through thin volcanic flows. It is located 281 nautical miles north of Saipan and has an area of 0.8 square miles. The three islands are the remains of a partly submerged volcano that surrounds a deep and spacious natural harbor. Steep cliffs border the islands. On the north and west islands there are columns resembling tombstones which crown the ridges, (out crops of basaltic veins). It is uninhabited and the highest point is North Island at 746 feet.
Natural threats: cyclones.
Human impact: former Japanese weather station and fish processing plant 1939-1944; otherwise uninhabited since 1695.
Ecosystems: scrub and grasses, coconuts on East Island; rocky shore and Lagoon with algal mat scattered corals; fringing reef off West Island.
Special features: seabird rookery; proposed as marine sanctuary.
Special of conservation interest
Plants: 59 species including several group endemics but no island endemics Lysimachia mauritiana.
Birds: 11 seabirds, 2 shore birds, 3 land birds: Megapodius laperouse laperouse (Marianas Megapode) group endemic subspecies, Rare (RDB) Aplonis opacus aeneus (Micronesian starling) subspecies endemic to northernmost Mariana Islands Halycon chloris owstoni (white-collard Kingfisher) subspecies endemic to the northernmost Mariana Islands.
Mammals: Pteropus mariannus (Marianas fruit bat) group endemic.
Marine life: 232 fish species, 130 invertebrate species including 24 opisthobranchs, 60 algae.
Protected under the constitution (strict nature reserve 1) 2000ha.
Natural conservation status 3.
Ecosystem richness 0.
Species richness 1.
Economic pressure 0.
Human threat 0.
Natural vulnerability 1.
Practicality of conservation action 3.
Reliability of data 2.
Human Impact 0.
Conservation Importance 15
Uracas Maug Ascuncion Agrigan Pagan Alamagan Guguan Sarigan Anatahan Medinilla
Saipan Tinian Aguihan Rota Guam
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