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.
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).
BirdLife International (2021) Important Bird Areas factsheet: Great Isaac Cay. Downloaded from http://www.birdlife.org on 18/01/2021.