Morro de Castelo Branco is a natural reserve, formed by several geological strata, which, due to its vertical slopes and white colour, resembles a castle, thus receiving this designation. It results from a volcanic eruption which occurred about 30,000 years ago.
Due to its geophysical characteristics and isolation, it is a very important nesting site for seabirds, namely the Cory’s shearwater (Calonectris diomedea borealis), between March and October, the Common tern (Sterna hirundo) and the Barolo shearwater (Puffinus assimilalis baroli ).