Scientists in Hawaii fear warmer temperatures as a result of climate change will make avian malaria a bigger threat in the state.
Last month's US federal report, the Fourth National Climate Assessment, concluded climate change poses a threat to all the US, but particularly Hawaii and the American Pacific territories.
One of the writers of the Hawaii section of the assessment, the director of the Pacific Island Ecosystems Research Center, Gordon Tribble, said Hawaii was the most ecologically diverse US state.
He said the effects of climate warming were already apparent with forest birds facing a growing threat from malaria.
Dr Tribble said temperature was the limit on the mosquito which is the vector for the malaria.
"As a result higher elevations across the state have been refuges for forest birds where they do not contract malaria and the populations there have persisted. What we are seeing over time, and mostly notably on the island of Kauai has been a decrease in forest bird populations at high elevations."