Impacts of Introduced Avian Diseases on the
Decline and Extinction of Native Hawaiian Honeycreepers

It is becoming increasingly clear that the introduction of Culex mosquitoes and avian pox and malaria to the Hawaiian Islands has had landscape level impacts on the geographic distribution of highly susceptible native Hawaiian honeycreepers. The Pacific Island Ecosystems Research Center (PIERC) has taken a leadership position in identifying the role these diseases continue to play on the decline and extinction of native forest bird communities. Past accomplishments include development of new diagnostic tools for detection of disease, surveys of critical forest bird habitats in the islands to determine the status of disease and vector distribution, and tests of the effectiveness of habitat management as a method for controlling mosquito populations. Ongoing research efforts at PIERC are developing a better understanding of disease and vector ecology, investigating the natural evolution of resistance to these diseases in some species of native honeycreepers, and testing potential management strategies that can be adopted by Federal, State, and private agencies in Hawaii.

Anianiau from the Alakai Wilderness Preserve, Kauai

Fig. 1. Anianiau (Hemignathus parvus) from the Alakai Wilderness Preserve, Kauai. This species is currently restricted to high elevation montane rain forests on Kauai. Like other native honeycreepers, Anianiau are highly susceptible to avian pox and malaria and have disappeared from former low elevation habitats because of mosquito transmitted avian diseases.

Fig. 2. Foot lesions caused by avian pox virus. The large swellings caused by the virus make it difficult for birds to perch and forage. Vision may be impaired when lesions occur around the eyes and beak.

Fig. 3. Blood smear from a native honeycreeper with avian malaria. The malarial parasites (Plasmodium relictum) attack red blood cells and cause severe anemia. Birds with acute infections are unable to forage and are easy prey for introduced predators.

Fig. 4 Culex quinquefasciatus, the southern house mosquito, was accidently introduced to the Hawaiian Islands in 1826. This spread of this vector of avian malaria and pox throughout the Hawaiian Islands was hastened by the creation of aquatic larval habitats by human and feral pig activity.
Photo by Jack Jeffrey.

Hawaiian Endangered Forest Birds

Impacts of Introduced Avian Diseases on theDecline and Extinction of Native Hawaiian Honeycreepers

Impacts of Introduced Avian Diseases on the
Decline and Extinction of Native Hawaiian Honeycreepers