There is no consensus among authors about the origin of the name of this archipelago. The most commonly accepted version says that the toponymy would be due to the large amount of excrement (in Portuguese, "cagádas" ) of seabirds that live, nest and feed on these islands. After feeding mainly on fish, these birds excrete their feces, rich in calcium, on the rocky slopes of the islands, staining them white. This hue is clearly visible from the shore of
Ipanema, one of the south beaches of Rio de Janeiro In 1730, its main island, appears on a nautical chart with a Frenchified name "Island Cagade." In another letter, dated 1767, the same appears with the island carrying its name in Portuguese: "Crappy Island." "Ilha Cagáda" Another possibility for its name is that Portuguese sailors wrongly identified the frigatebirds (fragatas in Portuguese) that nest on these islands, with the Cory's shearwater (cagarras in Portuguese) seabirds that live in the archipelagos of
Madeira and the
Azores (Portuguese territories): the
shearwater or cagarra (
Calonectris borealis) is not found on Brazilian islands. ==History of the Archipelago==