The San Nicolas Bay Reef Islands are an Important Bird Area for Aruba under the Birdlife International protocol of important bird areas in the Caribbean. The area has been denominated as IBA AW004.
The area is made up of five small, low-lying, boulder-coral reef islets situated off the south coast of south-easternmost Aruba, within San Nicolas Bay. The group of islands is separated from mainland by a shallow lagoon next to a large oil refinery and the town of San Nicolas.
The area gained IBA status because it is significant for nesting gulls and terns. Birds present in globally important numbers include: Laughing Gull (Larus atricilla) — 800 birds; Sandwich ‘Cayenne’ Tern (Sterna sandvicensis eurygnatha) — 1,300–3,500 pairs; Roseate Tern (S. dougallii) and Common Tern (S. hirundo) which use the area as a breeding site. Other species that also breed in regionally important numbers include: Royal Tern (S. maximus); Least Tern (S. antillarum); Bridled Tern (S. anaethetus); Sooty Tern (S. fuscata) — 14,340 birds; Brown Noddy (Anous stolidus) and Black Noddy (A. minutus). The nesting season is primarily between early April and mid-August.
The endemic Aruban Whiptail Lizard (Cnemidophorus arubensis) occurs in the IBA. Queen Conch (Lobatus gigas) are relatively abundant within the IBA. Globally threatened sea turtles are occasionally observed in the waters surrounding the area.Source: BirdLife International. (2008). Important Bird Areas in the Caribbean: Key sites for Conservation. Cambridge, UK: BirdLife International. (BirdLife Conservation Series No. 15).