The Iago sparrow (Passer iagoensis), also known as the Cape Verde or rufous-backed sparrow, is a passerine bird of the sparrow family Passeridae. It is endemic to the Cape Verde archipelago, in the eastern Atlantic Ocean near western Africa. Females and young birds have brown plumage with black marks above, and a dull grey underside, and are distinguished from other species of sparrow by their large, distinct supercilium. Males have a brighter underside and bold black and chestnut stripes on their head. At 12.5–13 centimetres (4.9–5.1 in) long, it is a smaller sparrow. This bird's vocalisations are mostly variations on its chirp, which differ somewhat between males and females.