The Greater Koa Finch (Rhodacanthis palmeri) was a species of finch in the Fringillidae family. It was found only in the Hawaiian Islands. It has been extinct since the late 19th century.
The bird was about 10 in (23 cm) long when fully grown. It was the largest known honey-creeper, although its typical weight is unknown. The bird is sexually dimorphic; the male was brilliant scarlet-orange on head, neck, and breast, with lighter orange on its bottom, and olive brown with orange touches on back, wings, and tail; however, the female was brownish olive, and somewhat lighter below. It had a thick black bill which allowed it to break open seed pods that were found in the trees. It was confined in all of its range, its range was on the Big Island of (Hawaii, in which it lived mostly in the Kona District. Neighboring species of this bird included, the closely related lesser koa finch (Rhodocanthis flaviceps), and the Kona grosbeak. Perkins had mistook the call of this bird to be the song of the Kona Grosbeak. The Lesser and Greater Koa Finches were once thought by scientists to be the minimum and maximum growth of a single species of Koa Finch.
The birds probably sipped nectar from several flowers that grew on trees, like the mamane and the O'hia tree.
Like its close relative the Lesser Koa Finch, this bird lived in small stretches of forest in both dry and wet areas of the Big Island of Hawaii. It's wet forests were the first to be cut down to create farm land. As soon as that land went poor, the people cut down the dry forests and irrigated the land which caused the land to go from dry to wet - thus exterminating the bird's environment. Cattle which also raised in the area destroyed much if not all the understory environments of the Kona District forests, allowing the trees to die out and lead to the same condition as uncontrolled farming, poor, unusable land. The last birds were probably eaten up by pests, both indigenous and European. These creature also caused the birds to get sick, their eggs were eaten right in the nests, and the birds were themselves eaten. They were exterminated in the years 1894-1896.
- BirdLife International 2004. Rhodacanthis palmeri. 2006 IUCN Red List of Threatened Species. Downloaded on 10 July 2007.