Meeting Abstract

P2.43  Tuesday, Jan. 5  Introduced vector-borne disease in native and introduced Hawaiian forest birds on Oahu KREND, KL; University of Hawaii at Manoa krend@hawaii.edu

Avian diseases, such as malaria and avian pox, are recognized as the most important factor preventing recovery of Hawaiian forest bird populations in low elevation habitats. This study investigated malaria and pox at 6 sites on Oahu in over 15 species, including two native species, the apapane and Oahu amakihi. Several species were identified as reservoirs of malaria, including house finches (68% infected individuals), chestnut mannakins (34%) and apapane (33%). Prevalence of pox was lower than malaria, with the highest incidence of pox-like lesions found in house finches (26%), northern cardinals (12%) and apapane (11%). Logistic regression indicated that the probability of an individual bird testing positive for malaria varied among species and sites in both native and introduced birds. Malaria was associated with pox-like lesions in native species, but not in introduced species. This suggests dual transmission of both diseases by the mosquito vector, but greater resistance or tolerance to pox virus in introduced species. Introduced species may be exposed to both diseases at the same rate as native species, but their longer evolutionary histories with blood parasites and viruses likely cause differential immune responses. Native Hawaiian species were not exposed to vector-borne disease until both pathogens and the mosquito vector were introduced beginning in the late 1800s. Some species of introduced birds are likely acting as reservoirs of pox and malaria, and their high abundance will maintain the disease reservoir at high levels. However, the continued presence of Oahu amakihi and apapane in some forests of Oahu may indicate these species are evolving resistance or tolerance to these diseases.