Avian malaria is a mosquito-borne disease of birds caused by a protozoan parasite (Plasmodium relictum). P. relictum reproduces in avian red blood cells. If the parasite load is sufficiently high, the bird loses red blood cells (anemia). Because red blood cells are critical for moving oxygen about the body, loss of these cells can lead to progressive weakness and, eventually, death.
This disease was introduced to Hawaii and native honeycreepers are highly susceptible. Avian malaria has contributed to population declines and extinction of Hawaiian forest birds. USGS scientists are investigating population impacts and how the dynamics of this disease change with elevation and climate change.
Hawaiian forest bird populations have been negatively affected by the non-native avian malaria parasite. In 2015, the USGS was a partner in the development of models to (1) understand avian malaria dynamics in different species and at different elevations and (2) forecast avian malaria risk in light of climate change. Malaria infections are highest at low elevations and over 90 percent of infected scarlet Hawaiian honeycreepers (I’iwi) die from this disease.