Mariana Swiftlet Aerodramus bartschi

A tiny, all-dark swift. Flight is fast, fluttery, and batlike. Usually observed flying continuously along ridges or over the forest canopy. Native to the Mariana Islands; introduced to Hawaii from Guam in the 1960s. In Hawaii, occurs only in the mountains of Central Oahu, seen primarily in Halawa Valley and the adjacent Aiea Loop Trail.