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| Annual meeting of The Wildlife Society, Sept 24-28, 2002, Bismark, ND
Symposium: Diseases of wild birds: ecology, management and effects on populations
Ecology and evolution of introduced diseases and disease vectors in Hawaii: role of avian pox and malaria in the demise of an endemic avifauna. ATKINSON, CARTER T., VAN RIPER III, C., BANKO, P.C., DOBSON, A.P., DUFFY, D.C., FLEISCHER, R.C., FONSECA, D.M., JARVI, S.I., LAPOINTE, D.A., SAMUEL, M.D., AND WOODWORTH, B.L. The introduction of mosquitoes (Culex quinquefasciatus) and both avian pox (Poxvirus avium) and malaria (Plasmodium relictum) to the Hawaiian islands has had an enormous impact on native forest bird communities and is believed to be one of the primary factors responsible for their collapse at lower elevations. We have documented the impacts of these diseases through studies of their distribution, pathogenicity, vector ecology, and epidemiology and are currently investigating the biocomplexity of the disease system at spatial scales ranging from the gene to the landscape. Epidemic outbreaks are seasonal, dependent on vector populations, and are driven by variable environmental conditions across an elevational gradient, host immunity, and complex interacting factors that include host, parasite and vector genetics. Restoration of Hawaiian forest bird communities will depend on aggressive and creative management strategies that incorporate detailed knowledge about the dynamics of this disease system across large landscapes. |
| North American Ornithological Congress, Sept 24-28, 2002, New Orleans, LA
Symposium: Avian diseases Introduced pathogens and persistent bird populations in Hawaii: Biocomplexity of an evolving disease system. BETHANY L. WOODWORTH, CARTER T. ATKINSON, DENNIS LAPOINTE, PAUL BANKO, SUE JARVI, ROBERT FLEISCHER, DINA FONSECA, MICHAEL SAMUEL, ANDREW DOBSON, DAVID DUFFY, PATRICK HART, ERIK TWEED, KELLY KOZAR, CARLENE HENNEMEN, TAMI DENNETTE, CALEB SPEIGEL, DAN LEASE, AARON GREGOR, KIARA BANKS, AND PEGGY FARIAS. The introduction of mosquito-borne avian malaria (Plasmodium relictum) and pox (Poxvirus avium) to Hawaii are known to have had severe detrimental impacts on the native avifauna, leading to restriction of most native birds to high elevation refugia where mosquitos are rare. Recent emergent phenomena, such as persistence of some native bird populations in low-elevation habitats, indicate that this system is still evolving. Our studies show that native Hawaii Amakihi (Hemignathus virens) are resident and breeding in low-elevation forests in densities approximately 2-3 times those found at high elevations. Amakihi persist despite malaria prevalence rates of 60-90%, with a single host infected with up to 9 variants of P. relictum. Malaria-infected Culex quinquefasciatus occur at all three low-elevation sites, demonstrating local disease tramission. Laboratory challenge experiments lend support to the idea that the primary reservoir of avian malaria at low elevations on Hawaii is the Hawaii Amakihi. The genetic, epidemiological, immunological, and demographic basis for persistence of these populations is the subject of ongoing research. Understanding the mechanisms by which low-elevation native bird populations persist may hold the key to long-term preservation of the Hawaiian avifauna. |
| Hawaii Conservation Conference, July 18-19 2002, Honolulu, HI Introduced pathogens and persistent bird populations in Hawaii: biocomplexity of an evolving disease system. BETHANY L. WOODWORTH, CARTER ATKINSON, DENNIS LAPOINTE, PAUL BANKO, SUE JARVI, ROBERT FLEISCHER, MICHAEL SAMUEL, DINA FONSECA, DAVID DUFFY, ANDREW DOBSON, PATRICK HART, ERIK TWEED, KELLY KOZAR, CARLENE HENNEMEN, TAMI DENNETTE, CALEB SPEIGEL, DAN LEASE, AARON GREGOR, KIARA BANKS, AND PEGGY FARIAS. Avian malaria and pox are known to have severe detrimental impacts on native bird populations in Hawaii, leading to the near-absence of native birds from most low-elevation habitats, where mosquito vectors are abundant. The "Biocomplexity of Introduced Avian Disease" project is investigating host species, vectors, and parasitic infections in 9 ohia-dominated forests from sea level to 5400 m on eastern Mauna Loa. We have detected year-round presence of the southern house mosquito (Culex quinquefasciatus), the vector of avian malaria, in 3 low-elevation forests. Mosquitos infected with malaria have been found at all 3 sites, demonstrating that local disease tramission is occuring. Nonetheless, the forests continue to harbor high densities of the native Hawaii Amakihi (Hemignathus virens). Amakihi are resident and breeding at low elevations in densities approximately 2-3 times those found at high elevations (16.2 birds captured/100 net-hrs and 5.7 birds/count period at low elevations, compared with 5.7 birds/100 net-hrs and 2.1 birds/count period at high elevations). Amakihi persist despite extremely high prevalence rates of malaria (60-90% of birds infected). Laboratory challenge experiments lend support to the idea that the primary reservoir of avian malaria at low elevations on Hawaii is the Hawaii Amakihi. The genetic, epidemiological, immunological, and demographic basis for persistence of these populations is the subject of ongoing research. In the face of expanding mosquito populations and continued threat of disease, understanding how these populations persist may hold the key to preservation of other native bird species in Hawaii. |
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