Oʻahu nukupuʻu bill to pluck insects found underneath tree bark, the Oahu nukupuu fed on insects on flowering trees such as the koa ("Acacia koa") and ohia ("Metrosideros polymorpha"). These trees attract a large amount of insects due to their nectar-filled flowers. The Oahu nukupuu fed on koa in high elevation forests and fed on ohia in low elevations. The species was believed to have vanished as the spread of disease occurred, killing off nukupuu populations across the islands. In order to control the rat population in the sugar cane fields, mongooses were introduced to Hawaii and were suspected to be predators
Koa people their territory. In 1998 grazier Noel Kennedy applied to the Federal Court to have his property Castle Hill declared to be free of native title. This was challenged by the descendants of the Koa the following year, in a counterclaim for native title to the Castle Hill Pastoral Holding and the Bladensburg National Park in the Shire of Winton. In mid-2002 a Federal Court declared that the Koa claim did not apply to Kennedy's pastoral lands because the Koa could not demonstrate continuity of cultural practices in that area over the last half-century. In 2015, a further claim to title