Current view: Text account
Site description (2007 baseline):
Site location and context
Five small (1.75km2) low lying (max height 3m), boulder-coral reef islets located at the south-east corner of Aruba. The islands are located within San Nicolas Bay separated from the mainland by a shallow lagoon (3m-15m) adjacent to a large oil refinery and the town of San Nicolas. Hurricanes, winter storms and heavy rains have changed the size, substrate and extent of vegetative cover on the islands. Human disturbance and egg collecting has been minimized through public awareness and education. Informal protection provided by the refinery staff with regular patrols by the coastguard.
A significant regional site for Cayenne tern (1,300 – 3,500 prs.), black noddy (26-48 prs.) , roseate tern (25-75 prs.) and common tern (10-30 prs.). The site also includes sooty terns (2,000 - 6,600 prs.), brown noddy (120-180 prs.), bridled terns (3-150 prs.), least tern (5-85 prs.), and up to 10 prs of sandwich tern and royal tern. The timing of nesting is primarily between early April and mid-August, although black noddies may nest outside of this period.
Non-bird biodiversity: Aruban whiptail lizards Cnemidophorus arubensis have been recorded on the islets; turtles are occasionally seen in the waters surrounding the islands; they are not known to breed on the islets. Queen conch (Strombus gigas) is relatively abundant (but not quantified) south of the San Nicolas Bay Reef Islands.
Three of the five islands are covered with a variety of salt-resistant plants that have become more prolific in recent years. The vegetation is dominated by buttonwood (
Conocarpus erecta), sea purslane (
Sesuvium porlulacastrum) and bay cedar (
Suriana maritme). The substrate includes sand, shell and is dominated by boulder coral.
Pressure/threats to key biodiversity
Human disturbance by recreational visitors during April – August is the primary threat to nesting terns. A proposal for a new hotel complex within 1.5km of the islands poses a threat from water-sports enthusiasts who may venture to the islands. During nine years of intensive study there have been no significant incidents or threats from the oil refinery to the terns. Laughing gulls (
Larus atricilla) represent a significant threat to nesting terns, particularly Cayenne terns, and account for 85% of egg and chick (<4–day old) mortality. Laughing gulls significantly affect overall breeding success particularly when Cayenne terns nest in small groups.
Conservation responses/actions for key biodiversity
Preliminary surveys and conservation awareness initiated in 1984 (Halewyn 1985). A detailed study of tern population ecology has been conducted since 1999 by Dr. Adrian del Nevo (Applied Ecological Solutions Inc.) in collaboration with the government of Aruba, the various owners of the oil refinery and Caribe Alaska. Conservation efforts have included school involvement, a television documentary and annual newspaper articles.
The islands were designated for protection in 1996.
We are very thankful to the author of this information Dr. Adrian del Nevo, and Theo Wools and Facundo Franken for their review.
Recommended citation
BirdLife International (2024) Important Bird Area factsheet: San Nicolas Bay Reef Islands (Aruba (to Netherlands)). Downloaded from
https://datazone.birdlife.org/site/factsheet/san-nicolas-bay-reef-islands-iba-aruba-(to-netherlands) on 23/11/2024.
