The Oahu alauahio, or the Oahu creeper, is a small honeycreeper bird endemic to Oahu, meaning it is native and found nowhere else. According to the International Union for Conservation of Nature Red List, it is presumed extinct.
Very little is known about the Oahu alauahio. It was once found in the Koolau and Waianae areas of Oahu, says the Department of Land and Natural Resources website. The webpage describes the males as “olive-green above with bright yellow underparts and forehead, females are grayish-green above and yellowish white below.” The sound of the birds’ song was never recorded. They were insectivores, having diets of mostly insects.
The last confirmed sighting of an Oahu alauahio was in 1985, says birdfinding.info, with the last specimen collected in 1968. Both the sighting and the specimen were from the Poamaho trail near Wahiawa.
Many sightings since then were probably the result of confusion with the more common and still alive - though vulnerable - Oahu amakihi, birdfinding.info explained. The Oahu amakihi is Oahu’s last confirmed surviving endemic honeycreeper, and looks similar to the Oahu alauahio.
According to BirdLife International’s Data Zone website, the apparent extinction of the Oahu alauahio may have been driven by diseases carried by mosquitoes. However, the site also says, it is possible that the Oahu alauahio is not extinct at all - though it may still be critically endangered.
“It cannot yet be presumed to be extinct until all areas of remaining habitat have been thoroughly searched,” says the Data Zone page on the Oahu alauahio. So far, no one has been able to do that.
If the Oahu alauahio is still out there, then it may be found in the mountains. The Oahu amakihi was driven to higher elevations as its populations declined, says whatbird.com. As a fellow honeycreeper, the Oahu alauahio may have done the same.
In the late 1980s, a large portion of what was left of the Oahu alauahio’s habitat was destroyed in order to make Interstate H-3, according to a 1998 article found on Anthrosource's website. While the Oahu alauahio should have been protected under the Endangered Species Act, Senator Daniel Inoyue passed a bill to exempt Interstate H-3 from following environmental protection laws.
The IUCN Red List says that if the Oahu alauahio is still alive, then its population would be less than 50 birds, and most likely as few as one to seven individuals. The last assessment was in October 2016, and no birds were found.