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Location Bahamas, Bimini
Central coordinates 79o 6.00' West  26o 2.00' North
IBA criteria A4i
Area 650 ha
Altitude 0 - 6m
Year of IBA assessment 2010

Bahamas National Trust (Partner Designate)

Site description Great Isaac Cay is located about 18 nautical miles north-north-east of the Bimini Islands in the Northern Bahamas, and is only accessible by boat. The most prominent feature on the cay is the lighthouse which stands approximately 151 feet (46 metres) high. It was built in 1859, standing at the intersection of the NW Providence Channel, the Great Bahama Bank and the Straits of Florida. The lighthouse is still functioning although it has been abandoned since 1969 when the two keepers mysteriously vanished.

Key Biodiversity This IBA is significant for its significant numbers and high diversity of nesting seabirds including Bridled Tern Sterna anaethetus, Least Tern Sterna antillarum , Roseate Tern Sterna dougallii, Sooty Tern Sterna fuscata, Brown Noddy Anous stolidus and Laughing Gull Larus atricilla. Of these, three (Bridled Tern, Least Tern, Roseate Tern) are considered to be of High Concern by Waterbird Conservation for the Americas (Kushlan et al., 2002, The North American Waterbird Conservation Plan) and three (Sooty Tern, Least Tern, Roseate Tern,) are considered to be Caribbean At-Risk Species (Bradley and Norton, 2009, Status of Caribbean Seabirds). The Bridled Tern population is globally significant with 568 nest counted in 2009 (Kushlan, 2009). It is estimated that 2,300-2,500 breeding pairs of this species occur in The Bahamas (Bradley and Norton, 2009). Thus Great Isaac supports about 25% of the national population. This is a species that generally nests in small numbers at any particular site: an average Bahamian nesting site holds 20 pairs. The numbers of Bridled Terns nesting on Great Isaac is comparable to the largest known colonies in the Bahamas (630 on North Riding Rock, 400 on Romers Cay and 400 on Bushes Cay).

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Bridled Tern Onychoprion anaethetus breeding  2009  568 nests  medium  A4i  Least Concern 


IUCN habitat Habitat detail Extent (% of site)
Coastline Sea cliffs & rocky shores  major
Rocky areas Scree & boulders  major

Land ownership Government

Land use

Land-use Extent (% of site)
not utilised major

Protection status This site has conservation, historical and cultural heritage potential. From the point of view of both diversity of seabirds and for the protection of one of the nation’s largest Bridled Tern colonies there is a strong case for the establishment of a national park or other protected area encompassing Great Isaac Cay.

Access/Land-Owner requests Accessible only by boat.

References James A. Kushlan. August 2009. Survey report. (unpublished)Wikipedia Online. Great Isaac Cay, Bahamas

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Great Isaac Cay. Downloaded from on 25/10/2016

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