Primitive koa finch viscosa") berries, as these were observed being eaten by other species in the genus. The primitive koa finch is believed to have gone extinct some time after Polynesians first arrived in Hawaii, however very little else is known about this species. Due to its early extinction it is only known from fossil remains. Other Hawaiian honeycreepers are known to have become extinct or very rare due to habitat loss, introduced predators and avian diseases. It is possible the extinction of the primitive koa finch also involved these factors. BirdLife International 2004. Himatione sanguinea. 2006 IUCN Red List of Threatened Species.
Koa wilt mortality rate over several years due to Koa wilt. It is also a legume, giving it the ability to form symbiosis with nitrogen fixing bacteria, which has led to efforts to use koa in agroecological systems with crops such as coffee and cacao. Ecologically, koa is an important species because it is one of the few native trees that remains dominant in alien mixed forests on the Hawaiian Islands. Invasive species make up the majority of the State's current plant population. Koa trees also are important because provide a habitat for many native bird species. Historically, there were once two