The Time Is Now: Saving Maui’s Honeycreepers Before It Is Too Late

Fewer than 2,000 of the ʻākohekohe (left) remain and fewer than 200 of the kiwikiu (right) remain.

Left: NPS Photo, Right: C. Robby Kohley

Within the next ten years, many native Hawaiian honeycreeper species will be pushed to extinction by the uncontrolled spread of avian malaria—but it’s not too late to save them! With public input, The Department of the Interior will work with multiple federal agencies, organizations, and their partners to carry out a plan to save Hawaiʻi’s honeycreepers from extinction. The plan seeks to suppress southern house mosquito populations across Hawaiʻi to reduce the spread of avian malaria and give the honeycreepers a fighting chance to restore their populations.

Southern house mosquitoes are responsible for the transmission of avian malaria to honeycreepers across the Hawaiian Islands. 

Photo/CDC

This multistep plan is proposed to start on Maui to save two endangered honeycreeper species: the kiwikiu and the ʻākohekohe. Haleakalā National Park, the state of Hawaiʻi’s Department of Land and Natural Resources (DLNR), the U.S. Fish and Wildlife Service, The Nature Conservancy (TNC), and their partners are working together to coordinate these conservation efforts on the island.

On Maui, honeycreepers live on land that is managed by state and federal agencies. Because of this, the project will follow requirements set by the National Environmental Policy Act (NEPA) and Hawaiʻi Environmental Policy Act (HEPA). The NEPA and HEPA require federal and state agencies to assess the environmental effects of the actions they want to take before they decide to take them.

These environmental effects are evaluated through a process called an Environmental Assessment. There are key steps for the National Park Service to complete while conducting an Environmental Assessment for NEPA compliance. To learn more about the process and steps, visit the NEPA Policy page on nps.gov and click on NPS NEPA Handbook (2015).

The Environmental Assessment for this project has been published for public review and is available to view online. To participate as a member of the public, you can read the Evironmental Assessment, submit comments, and view upcoming public meetings.

Keep in mind that for some, the Environmental Assessment can be hard to understand because it uses scientific and legal jargon. In an effort to make sure information shared through the Environmental Assessment is accessible and easy to understand, this article breaks down some of its main topics.

What is Happening?

Honeycreepers live in cool, high-elevation areas of the island which throughout evolutionary history, were once safe from mosquitoes. But rising temperatures caused by climate change are allowing the invasive southern house mosquito to move into those areas that honeycreepers call home. Once there, the mosquitoes feed on the birds and spread avian malaria. Avian malaria is a blood-borne parasite passed to birds through mosquito bites. Because of the bird’s long-term separation from the mosquitoes, honeycreepers lost whatever resistance their mainland ancestors may have had to the disease—leaving them incredibly vulnerable to its effects. This means that even a single bite from an infected mosquito could be fatal.

If left unchecked, this invasive species will drive Maui’s native honeycreepers to extinction in as little as two years! Luckily, local biologists, policy makers, and conservationists are making it a priority to save the forest birds and ultimately protect Hawaiʻi’s natural and cultural heritage. The agencies and partners involved in this project are using their expertise and resources to develop the most effective ways to manage and monitor the proposed plan to suppress southern house mosquito populations. Keeping the southern house mosquito population low will reduce the spread of avian malaria and protect honeycreepers, giving them time and space to rebuild their population.

Incompatible Insect Technique

Through years of research and planning the project team has found that one of the most reliable ways to suppress southern house mosquito populations is to use the Incompatible Insect Technique (IIT). IIT is an insect population suppression technique currently used in the U.S. and other countries. This technique can be applied to various insect populations including Maui’s southern house mosquitoes. IIT is a long-term insect management technique that would be maintained and monitored until (A) the spread of avian malaria is reduced to a level that stabilizes threatened and endangered honeycreeper populations or (B) new techniques are developed.

When applied to Maui's southern house mosquito population, this technique would release incompatible male mosquitoes to mate with wild females currently living on the island. When incompatible males mate with the wild females, the resulting “litter” of eggs will never hatch. It’s important to note that female mosquitoes can only mate once in their lives. They store the sperm of their mate until they are ready to reproduce. So, the female mosquito has one chance to successfully choose a mate. If she mates with an incompatible male, she has lost that chance to introduce new mosquitoes into the wild. There is no chance for her to mate again before she dies. The repeated process of wild females mating with incompatible males successfully decreases the southern house mosquitoes.

To ensure the likelihood that a wild female mates with an incompatible male, scientists will determine the appropriate number of incompatible male mosquitoes to release. It is necessary for incompatible males in the area to outnumber the wild males.

Wolbachia

What makes the released male mosquitoes incompatible? There is a naturally occurring bacteria within the sperm and egg cells of southern house mosquitoes called Wolbachia. These bacteria exist in the majority of insects across the world, including here on the Hawaiian Islands! There are many different types, or strains, of Wolbachia that have evolved throughout the world. Some strains have become so different from one another that they can no longer reproduce. The inability for different strains of Wolbachia to reproduce between a sperm and an egg cell, also cause the host species, in this case mosquitoes, to lay sterile eggs (eggs that will never hatch). Scientists are using this biological phenomenon to their advantage through IIT.

Using the natural properties of Wolbachia through IIT is safer and more effective than common options like pesticides. Wolbachia are not bacteria that can be spread through physical contact or even an insect bite. It can only be passed on from mother to offspring through sexual reproduction. This means that birds, humans, and other species of insects are at no risk of getting Wolbachia. It can't even be passed between adult male and female mosquitoes!

Incompatible Insect Technique Continued

For IIT to be successful, only incompatible male mosquitoes can be released. If female mosquitoes with the same incompatible strain of Wolbachia were released, they would be able to successfully mate with the released male mosquitoes and increase mosquito population numbers—negating the intended benefit of this project by increasing mosquito population numbers. Increasing mosquito populations would worsen the honeycreepers’ situation. Because of this, extreme care would be given to sorting out female mosquitoes prior to releases.

The sorting would happen at laboratories where the mosquitoes would initially be bred for this project. Sounds intense, but it’s not! The laboratories will help ensure only mosquitoes with the specific incompatible strain of Wolbachia are being released. These facilities would most likely be in the mainland U.S., but the mosquitoes would be bred from mosquitoes captured here in Hawaiʻi. The mosquitoes would then be packaged, shipped to Hawaiʻi, and released shortly after their arrival.

Releasing Mosquitoes

The male mosquitoes would be strategically released to existing breeding grounds across East Maui primarily by drones. At times, some mosquitoes would need to be released by pedestrian teams or helicopters. The release process would be repeated at strategic intervals to make sure the southern house mosquito population continues to drop.

The aim of the project is to release incompatible male mosquitoes when and where mosquitoes are breeding, targeting those places where the mosquitoes are most threatening to the endangered birds. Scientists believe that during the coldest months on the island, mosquito breeding occurs mostly at lower elevations where temperatures remain warm. This overlaps with most honeycreepers’ breeding season. This is a benefit because fewer male mosquito releases would be needed in the high elevation areas during peak honeycreeper breeding season, leaving more protected time for the birds to rebuild their population! Releases would likely continue throughout the year at the lower elevation breeding grounds.

For the greatest impact, incompatible mosquitoes would be distributed anywhere from twice per week to once per month. The existing mosquito breeding grounds will be monitored to determine how well the program is working.

Release Methods

This project anticipates using drones as the main way of releasing the incompatible southern house mosquitoes. Drones provide a safe and efficient method for delivering mosquitoes across remote areas. Using drones would be less expensive and less noisy than using helicopters. The exact way in which the mosquitoes would be released from the drones and the precise drone model(s) have not been determined yet, but several models are currently available and being considered. Drone delivery has been successfully used elsewhere for other similar mosquito management plans and this project’s goal is to do the same! Considering drones’ limited impacts to wildlife and the public, they are seen as a uniquely superior release method.

In some cases, field technicians (pedestrian teams) may be needed to release the male mosquitoes by hand. Additionally, helicopters may be used as a temporary, short-term method of release. Throughout the project, helicopters would also be needed to transport teams into the field to monitor the southern house mosquito population.

Project Impacts

This project positively impacts Maui’s environment to save endangered and threatened honeycreepers. There is an Impact Analysis outlined in the project’s Environmental Assessment that describes the anticipated project effects and the actions planned to lessen or prevent any negative impacts. Highlighted below are two possible areas of interest regarding this project’s impacts: impacts to wilderness and impacts to the public. Other impacts are also assessed and discussed in the Environmental Assessment.

Wilderness

The Wilderness Act of 1964 established the National Wilderness Preservation System to preserve and protect certain lands in their natural condition. The Wilderness Act and the National Park Service require the preservation of wilderness through five measurable qualities: untrammeled, natural, undeveloped, and solitude or primitive. You will see these terms defined and used within the project’s environmental assessment.

The Environmental Assessment analyzed the potential impacts of this project within a total of 64,666 acres of East Maui. Of that, approximately 14 percent are within congressionally designated wilderness. Although the project would negatively impact certain qualities of the wilderness, such as the untrammeled quality, this project would benefit others, specifically the natural quality of the wilderness by preventing the extinction of species that make up an essential part of the wilderness.

For more information about wilderness impacts, see the bottom of page 37 of the Environmental Assessment.

Public

The proposed project will not impact mosquito populations in residential areas of the island. This means the public will not see a significant decrease in mosquitoes or mosquito bites while out and about. This is because (A) the mosquito being targeted by this project, the southern house mosquito, only bites at night and (B) this project will target breeding grounds in remote areas of East Maui, far away from residential areas. Similarly, the public will not notice a significant increase of mosquitoes in residential areas. All incompatible male mosquitoes will be released in remote areas of the island. Southern house mosquitoes do not typically travel far from their breeding grounds and males are thought to travel even less than females. Because of this, scientist do not believe the incompatible male mosquitoes will travel (nor have an effect) far from where they are released.

To learn more about mosquitoes on Maui, read the article on our park website!

What Can You Do?

It’s not too late to save the threatened and endangered honeycreepers on Maui! With science and swift action, the kiwikiu, ʻākohekohe, and other honeycreepers can rebuild their populations and continue contributing their beautiful songs and presence to the forests of the island.

We are all stewards of native Hawaiian wildlife. Haleakalā National Park and the State of Hawaiʻi need your feedback to save the honeycreepers from extinction. To provide feedback, read the Environmental Assessment and submit your feedback on the Haleakalā National Park Planning, Environmental Policy, and Compliance (PEPC) project website by January 23, 2023. You can also continue to share information about this project with your local community! You can visit Haleakalā National Park, Maui Forest Bird Recovery Project, and Birds, Not Mosquitoes to find shareable information about this project. Together we can save the honeycreepers and preserve the sacred wilderness of Maui.