Greater Koa Finch

The greater koa finch, known scientifically as Rhodacanthis palmeri, was a remarkable bird that graced the island of Hawaiʻi with its presence. This extinct species of Hawaiian honeycreeper was the largest of its kind, measuring a notable 7 to 8 inches in length. The males of the species were adorned with a brilliant scarlet-orange plumage on their head, neck, and breast, transitioning to a lighter orange on their underside. Their backs, wings, and tails were an olive brown with hints of orange. In contrast, the females were cloaked in a more subdued brownish olive, lighter on the belly. Both sexes boasted a robust black bill, perfectly evolved to crack open the tough seed pods they so favored.

Identification Tips

When identifying the greater koa finch, one would look for the striking sexual dimorphism between the males and females. The male's vibrant scarlet-orange plumage and the female's more muted tones would be key distinguishing features. The bird's thick black bill was another characteristic trait, designed for accessing the seeds within the hardy pods of the koa trees.

Habitat

The greater koa finch was endemic to the mesic forests of the Big Island of Hawaiʻi, with a historical range largely confined to the Kona District. These forests were dominated by the koa tree, which provided both sustenance and habitat for the finch.

Distribution

Historically, the greater koa finch was more widespread across the Hawaiian Islands before human settlement. However, by the time it was observed by scientists, its presence was largely restricted to the Kona District, with a notable sighting in the Kīlauea area in 1895.

Behaviour

This bird was known to live alongside its close relative, the lesser koa finch, as well as the Kona grosbeak. It was once believed that the greater and lesser koa finches represented the extremes in size variation of a single species, but they were later recognized as distinct.

Diet and Feeding

The greater koa finch was primarily a granivore, with a particular preference for the pods and seeds of the koa tree. It also supplemented its diet with caterpillars and the seeds of the ʻaʻaliʻi shrub.

Conservation status

The greater koa finch is classified as extinct, with the last confirmed sighting in 1896. The decline of this species was attributed to habitat loss from logging and conversion to pasture, grazing by cattle, predation by introduced black rats, and diseases such as avian pox and malaria spread by mosquitoes. The loss of lowland koa forest even before these pressures suggests that the finch was already in a precarious position due to habitat degradation.