WatchList Species Account for ‘I’iwi (Vestiaria coccinea)

Qualifies for the list as a Red List Species

Photo: © Jack Jeffreys

The ‘I’iwi, a spectacular bird with brilliant red and black feathers, has one of the larger distributions for a species endemic to the Hawaiian Islands. It is found on Hawaii, Maui, Kauai, Oahu, and Molokai, though on the latter two islands it probably numbers only about 50 individuals. Formerly it was one of the most common forests birds, found on all forested islands to sea level, but it has disappeared from most of its former range, though still relatively common in high elevation forests on the island of Hawaii. It is difficult to census since it makes long flights over the forest in search of the flowers of ‘ohi’ a trees, its primary food source. Though total numbers are estimated at 350,000, the majority of which are on Hawaii, the bird is thought to be undergoing a population decline, except at higher-elevation sites.

The ‘I’iwi is found mainly in wet or moderately wet forests where 'ohi'a and koa are the dominant trees but also in dry mamane forest, though it does not often breed there. It is found predominantly above 1,250 m, above the range of disease-carrying mosquitoes. It feeds not only on nectar of 'ohi'a but also of mamane and introduced banana poka. It also catches butterflies, moths, other insects, and spiders.

As is the case with other native Hawaiian forest birds ‘I’iwis have declined because of habitat loss, avian disease, and the introduction of alien plants and animals. The 'I'iwi is extremely susceptible to avian malaria and avian pox, which are both transmitted by mosquitoes and in fact mosquito-transmitted diseases seem to impact it more than they do other native honeycreepers. If cold-tolerant mosquitoes were introduced to the Hawaiian Islands, it could spell disaster for the ‘I’iwi and most other native forest birds. In the meantime, the ‘I’iwi has benefited from efforts instituted to benefit more endangered forest birds by restoring native forest, controlling spread of alien plant species and introduced mammalian predators, particularly rats and cats, and eliminating feral pigs, whose activities create breeding places for mosquitoes.