Pacific Island Ecosystems Research Center
| Home Page About Us Research Publications Learning Center Fact Sheets Field Stations Search Staff Contact Us |
| A large proportion of forest birds native to the Hawaiian Islands have become endangered or extinct since European settlement. Several potential causes have been identified, including avian diseases introduced and exacerbated by human encroachment on native ecosystems. Studies by Richard Warner in the 1950's and Charles van Riper III in the 1970's have suggested that disease, particularly avian malaria and avian pox, may be limiting the current distribution and abundance of native forest birds. Primary objectives of this project are to develop a better understanding of the current geographic and elevational distribution, epidemiology, reservoir hosts, and impacts of these two diseases on forest bird populations. Results will be used to develop and test disease control strategies to prevent further declines in native forest bird populations. |
| Akiapola'au (Hemignathus munroi) from the island of Hawaii (right) was once found at elevations as low as 500 m. This endangered honeycreeper now occurs in only a few remnant populations in high elevation ohia and koa forests |  |
 |
such as those at Hakalau Forest National Wildlife Refuge (left). Temperatures at elevations higher than 1,500 m limit the mosquito vector of pox and malaria in Hawaii, Culex quinquefasciatus. |
| Student Conservation Association Resource Assistants carry sentinel chickens and canaries to a remote location in Hawaii Volcanoes National Park. The birds are exposed in cages in the forest canopy to monitor natural transmission of pox and malaria. After several weeks in the field, birds are brought back to a mosquito-proof aviary and held to see if pox lesions (lower left) or malarial infections develop. This method has been useful in identifying specific locations in the park where disease transmission is occurring. |  |
 |
 |
| Long term studies of the prevalence of pox and malaria at Hawaii Volcanoes National Park, coupled with surveys of these pathogens in critical forest bird habitats on the islands of Maui and Kauai (right) are helping to unravel the epidemiology and current elevational distribution of the diseases. A Student Conservation Association Resource Assistant (lower left) removes an Iiwi (Vestiaria coccinea) from a mist net. The bird is then banded, bled, and released. Microscopic (lower right), serological, and molecular analyses of the blood sample provide information about status of malarial infection and genetics of both the host and parasite. This latter information may prove critical for understanding the seasonal disease outbreaks that occur in some habitats and how parasite virulence and host resistance are coevolving in some species of honeycreepers. |  |
 |
 |
| Forest birds (right) that are found dead during seasonal outbreaks of pox and malaria are necropsied to determine cause of death. This information has helped us confirm that pox and malaria are still the primary pathogens among native species. Birds suffering from acute malaria have the characteristic gross lesions of the disease, including enlargement and discoloration of the liver (lower right). Birds with pox infections have viral inclusion bodies in pox lesions (lower left) that are diagnostic for this disease. Individuals may be infected with both diseases at the same time. |  |
 |
 |
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://biology.usgs.gov/pierc/
Page Contact Information: Send mail to Webmaster
with your questions or comments
Page Last Modified: Friday, Dec 1, 2006
