O’u †

Endemic to Hawaii, but presumed to be extinct.

In historical times it occurred on all the major islands with forested hills: Kauai, Oahu, Molokai, Lanai, Maui, and the Big Island.  It is thought to have been somewhat nomadic in search of fruiting trees, and apparently migrated within the islands, and sometimes from island to island.

Its most favored habitat was likely ohia-dominated forest at elevations of about 300 to 1,200 m, but it also occurred across a broader set of habitats, from sea level to at least 2,100 m.

During the 1800s it was reportedly abundant on the six largest islands, but toward the end of that century it declined rapidly on most islands, and disappeared from Oahu around 1900, Maui and Molokai around 1910, and Lanai around 1930.

Populations that were estimated in the dozens or low hundreds persisted on Kauai (mainly in the Alakai Swamp) and the eastern side of the Big Island (from Upper Waiakea Forest Reserve south to the national park and east to Puna Forest Reserve) into the late 1970s, then dwindled rapidly in the 1980s, with no confirmed records after 1989.

Avian malaria appears to be the primary cause of its extinction, and the species’ proclivity for descending to lowlands probably ensured that no portion of the population avoided contact with malarial mosquitoes.