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Hawaiʻi approves mosquito-suppression plan to help threatened birds

Iʻiwi, a bird threatened by mosquito-borne avian malaria.
An ‘I’iwi seeks nectar from the yellow flowers of māmane shrubs. Photo by Kendall Collett/Shutterstock

In late March, Hawaii’s Board of Land and Natural Resources (BLNR) unanimously approved a plan to employ landscape-scale mosquito suppression in critical forest-bird habitat to reduce mosquito populations in the dense, wet forests of east Maui.

The purpose of the project is to prevent the extinction of threatened and endangered forest birds. Avian malaria, a fatal disease, is the primary cause for the dramatic decline for six remaining species of Hawaiian honeycreepers: ‘I‘iwi, Maui ‘Alauahio, Hawai‘i ‘Amakihi, ‘Apapane, Kikiwiu, and ‘Ākohekohe.  For critically endangered species, like Kiwikiu and ‘Ākohekohe, the increasing presence of invasive mosquitoes has put them on a trajectory for extinction within the next two to ten years.

The mosquitos that spread avian malaria are unable to successfully reproduce in cold environments, thus, these honeycreepers have been able to persist in high-elevation native forest habitat on east Maui. Increasing temperatures associated with climate change are allowing mosquito populations and avian malaria to expand into these high-elevation native forests, where some of the last populations of these forest birds remain.

The DLNR and the National Park Service (NPS) jointly produced a Final Environmental Assessment that proposes using a proven method known as Incompatible Insect Technique (ITT) to control invasive mosquitoes in the forests to reduce the incidence of avian malaria, which is fatal.

IIT has been used successfully worldwide to limit the human health impacts of mosquitoes and to reduce populations of the southern house mosquito, which spread avian malaria. The technique uses a naturally occurring bacteria called Wolbachia. Male mosquitoes, with an incompatible strain of Wolbachia bacteria, are released to mate with wild female mosquitoes that lay eggs that do not hatch. The result is much smaller populations of mosquitoes. Male mosquitoes do not bite and cannot spread diseases.


The EA reviewed the potential impacts of the proposed project, which would address parts of Haleakalā National Park, several forest reserves managed by DLNR, and private land parcels in east Maui. The comprehensive 300-page assessment considered the impacts of taking no action, an analysis of cultural resources in the project area, and addressed specific comments provided by community members on an earlier draft.

Based on the assessment, the NPS announced on March 23 that it would issue a Finding of No Significant Impact (FONSI) for the project, clearing the way for ITT to proceed on federal lands within the project area. Friday’s BLNR decision allows the project to also move forward on proposed state and private parcels.

“This is an emotional issue for people,” said BLNR Chair Dawn Chang. “These birds are part of our cultural and ecological heritage, and I think everyone wants to see them protected in the right way. Whether in support or opposition, we appreciate everyone who provided their manaʻo on this topic so the board could make an informed decision on the adequacy of the EA. What we do know is that taking no action, will put these valuable manu or birds at further risk of extinction.”


Both DLNR and the NPS are members of Birds Not Mosquitoes, a collaboration of state, federal, and private non-profit partners working to save Hawaiian honeycreepers from extinction.

Thanks to the Hawaiʻi Department of Land and Natural Resources for providing this news.

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