the whole region is typically wet, with marshes spreading throughout, especially to the east, where most of the biological reserve is situated.

these terrains contain an remarkably complex ecosystem and the huge flocks of birds create a very characteristic sight - in fact, these very flocks are the reason behind the region's name, as the word 'guaratiba' derives from a word meaning 'gathering of birds' in the indigenous tupi language.

ilha do cavado, the islands nearby, and marambaia island are characterized for the specific type of habitat they feature - called 'restinga', it is a type of sandy terrain usually found in the salt-water coastal regions of  tropical south america.