The species was abundant until the 19th century, when the loss of its lowland forests to slash and burn farming methods damaged its habitat.

The last confirmed sighting was in 1899; if the species survived after this time, it likely became confined to the Alakaʻi Wilderness Preserve.

From 1984-1998, it was recorded several times in this area, but later analysis of these sightings indicates that almost all these observations were likely of Kauaʻi ʻamakihi (Chlorodrepanis stejnegeri).

Intensive searches for this species throughout the 1990s were unsuccessful, although a single unconfirmed report was made in 2007.

Fish and Wildlife Service proposed that the Kauaʻi nukupuʻu should be declared extinct, citing fruitless and extensive surveys.