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Location Guam (to USA)
Central coordinates 144o 38.93' East  13o 14.17' North
IBA criteria A1, A2
Area 39 ha
Altitude 0 - 7m
Year of IBA assessment 2014

Summary Cocos Island (Chamorro: Islan Dåno) is an island 1 mile (1.6 km) off the southern tip of the United States territory of Guam, located within the Merizo Barrier Reef, part of the municipality of Merizo. The island is uninhabited, 1,600 meters (5,200 ft) long in a southwest-northeast direction, but only between 200 m (660 ft) and 300 m (980 ft) wide, and has an area of 386,303 m2 (95.458 acres).[1] It sits atop the southwestern coral reef rim of Cocos Lagoon.  The west coast of the island is a day resort. 

Key Biodiversity Green sea turtles nest on Cocos extensively, and it retains a reasonably robust coconut crab population, as well as several rare terrestrial lizards no longer found on Guam.

Virtually all the seabirds nesting around Guam are on Cocos Island.  This comprises Common White Terns, Brown Noddies and Black Noddies.  The numbers involved are only small, by global standards.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Guam Rail Hypotaenidia owstoni resident  2010-2014  26 individuals  medium  A1, A2  Extinct in the Wild 
Micronesian Starling Aplonis opaca resident  2010-2014  present  A2  Least Concern 

IBA Monitoring

2014 high favourable low
Good - based on reliable and complete / representative data

Human intrusions and disturbance recreational activities happening now small area/few individuals (<10%) no or imperceptible deterioration low
Invasive & other problematic species, genes & diseases invasive non-native/alien species/diseases - named species likely in long term (beyond 4 years) whole area/population (>90%) moderate to rapid deterioration high

Hypotaenidia owstoni Guam Rail 26 26 individuals 100 favourable

Unknown  A management plan exists but it is out of date or not comprehensive  Substantive conservation measures are being implemented but these are not comprehensive and are limited by resources and capacity  low 

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Cocos Island, Guam. Downloaded from on 25/10/2016

To provide new information to update this factsheet or to correct any errors, please email BirdLife