Unique to Atiu, unique in its features: the Kopeka (Atiu swiftlet). This little bird, not weighing more than 13 grams, has some serious technical features. While it´s got perfect sight to find its way when there is light, it also is equipped with sonar. It lives in the Anatakitaki cave – where it is mostly dark – and navigates by issuing click-sounds, which reflect of the cave walls and structures. And please remember, we are talking about a bird here, not a bat!