Development of an early warning system for climate-change related invasion by mosquitoes into Hakalau Forest NWR

A small, brown bird sits on the branch of a tree
Over half of the original 55 Honeycreeper species of Hawai'i have become extinct since human arrival to the islands over 1000 years ago, and more than half of those remaining are endangered. The primary reason for the continued decline of Honeycreepers is mosquito-transmitted diseases such as avian malaria (Plasmodium relictum). (Photo: SMladinich)
Park service sign for the Hakalau Forest National Wildlife Refuge in front of dense forest
Hakalau Forest NWR is home to the most intact native forest bird community in the state of Hawai’i and is traditionally viewed as being above the “mosquito zone”. (Photo: SMladinich)

Hakalau Forest National Wildlife Refuge (NWR) is home to the most intact native forest bird community in the state of Hawaiʻi. However, it is threatened by avian-disease-carrying mosquitoes, which are predicted to increase in abundance at the refuge over time due to global warming. This would lead to catastrophic effects on the native bird populations in one of their last strongholds. Under current bird and mosquito monitoring protocols, such an event would go undetected until it is too late.

Our research has four basic goals that will lead to the development and implementation of improved monitoring protocols to detect disease-carrying mosquitoes at Hakalau Forest NWR. Such protocols could also be applied to other high-elevation forest preserves across Hawaiʻi.

  1. Evaluate the current distribution and abundance of mosquito larvae habitat by surveying for pig-excavated tree fern cavities across Hakalau Forest NWR.
  2. Document the “lifespan” of these cavities, or the duration of their ability to hold water once they have been created.
  3. Examine the effect of elevation, temperature, and rainfall on the presence of mosquito larvae within the cavities.
  4. Determine the potential effectiveness of a new survey technique (acoustic monitoring) for detecting changes in mosquito abundance at the refuge over time.

Completion of these goals will provide information that allows managers to reduce larval habitat across the refuge and provide data for predictive models of mosquito distribution and abundance. Information from this study will also assist managers with the development of a much-needed early warning system for mosquito invasion across the refuge that will be useful in similar ecological zones across the state of Hawai‘i.

A student examines a sticky-looking sheet amidst a lush forest.
Undergraduate Timon Skinner checking the Gravid Aedes Trap (GAT Trap) used to detect mosquito presence as their range expands with increasing temperatures. (Photo: SMladinich)




Patrick Hart
Professor of Biology, UH Hilo


Stephanie Mladinich
Tropical Conservation Biology & Environmental Science, UH Hilo