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 Kannon no graves and thus no patrons under the danka system except for the surviving family of the seven war criminals. Koa Kannon is always requesting general help since the only thing maintaining the temple is offering money from visitors, volunteers, and members of support groups. One such association is the Koa Kannon Support Group, which was founded in 1942 by its first president Iwane Matsui and is preserved primarily by local devotees in Atami. There was in addition the Society to Protect the Koa Kannon which was established in 1994, but due to a scandal involving some of its board