Four species of the Hawaiian honeycreeper could disappear in the next few years, with conservation officials and scientists warning that disease and climate change are driving the palm-sized songbirds to extinction.

At fault is avian malaria, a disease carried by cold-intolerant mosquitoes. Warming temperatures have allowed the parasitic disease to encroach on forest habitats, pushing the endangered songbirds farther up the mountains. The sickness is relentless, killing over 90% of the honeycreepers it infects.

The dusky gray akikiki of Kauai and the chartreuse-yellow kiwikiu of Maui face the most immediate danger, as officials estimate both species number under 200 birds each and may become extinct by 2024, according to a cross-agency federal report published Thursday. Two other species, the akekee and the akohekohe, may vanish by the end of the decade, it said.

There are fewer than 200 akikiki left in the wild, and conservation officials warn the species could become extinct in less than two years. Courtesy: Kauai Forest Birds Recovery Project

“As many as 11 other Hawaiian forest birds are threatened with extinction in the coming decades if disease continues to spread,” U.S. Geological Survey ecologist Robert Reed said Thursday at a press conference at the state Department of Land and Natural Resources headquarters in Honolulu.

“Conservation strategies enacted now … may also help these other species and keep them from the brink,” he added.

Honeycreepers once filled Hawaii’s forests with their haunting melodies, flooding the skies with a painter’s pallet of mottled earth colors and the sunset’s many hues. Only 17 of more than 50 documented species of the songbird remain, and their rapid decline is partly due to the spread of avian malaria.

Neither the disease nor its host are native to the islands – mosquitoes were introduced to the islands in the 1800s aboard merchant and whaling ships flying under American and European flags. Avian malaria would follow, hitching a ride in the bloodstreams of nonnative birds, researchers theorize.

“The Hawaiian honeycreepers, they’ve evolved for 5 million years in the absence of malaria, and because of that, they’re highly susceptible,” University of Hawaii Hilo ecologist Kristina Paxton said in a separate interview.

Once injected by hungry mosquitoes, the single-cell parasite targets the honeycreeper’s red blood cells, causing anemia as the host slowly dies from lack of oxygen. One bite is enough to kill, conservation officials warn.

Honeycreepers were once able to seek refuge from the insects by roosting in cooler forests at higher elevations, where mosquitoes can’t survive and the parasite responsible for malaria can’t reproduce, said Paxton, who studies forest birds and the diseases that threaten them.

But climate change has deprived the birds of much of their usual range as warmer temperatures push mosquitoes to higher elevations, a significant problem for Kauai honeycreepers on an island that tops out at just 5,148 feet.

David Smith of the DLNR says the Hawaiian honeycreepers are losing “a huge amount of habitat.” Cory Lum/Civil Beat/2022

“We’re losing a huge amount of habitat,” said David Smith, director of the DLNR’s division of forestry and wildlife. “Right away, our first losses are some of our biggest.”

The only long-term solution to protect honeycreepers and other native birds is large-scale mosquito control, U.S. Fish and Wildlife Service field supervisor Earl Campbell told reporters.

One promising strategy involves inoculating male mosquitoes with the Wolbachia bacteria that leaves them essentially sterile. They’re then released into the wild in a method that has been likened to mosquito birth control.

The strategy has been successful against mosquitoes that carry the Zika virus and Yellow Fever in more urban areas, Campbell said. However, federal and state researchers face challenges in adapting the Wolbachia bacteria for forest mosquitoes carrying bird diseases.

“It really is a tech transfer issue,” Campbell said. “I’m thinking probably two to four years to try to start doing trials and implementation.”

In the meantime, researchers and officials are pursuing shorter-term, stopgap measures to preserve the remaining honeycreeper populations until mosquitoes can be controlled at a larger scale. One option involves taking birds into captivity, but that would be expensive and risks losing natural behaviors, the officials wrote in the report.

Another alternative is to relocate birds into areas free from mosquitoes. This also has had a mixed success rate. Researchers in 2019 attempted to relocate 13 kiwikiu honeycreepers from one side of Haleakala to the other, which they had thought was free of disease-ridden mosquitoes.

Within a month, almost all the parrotbills died from Avian malaria.

kiwikiu mosquito avian malaria
A researcher holds a dead kiwikiu honeycreeper after efforts in 2019 to protect the bird by moving it to a different area failed. Courtesy: Bret Nainoa Mossman/MFBRP

Despite the risks, Paxton said researchers and government agencies should do all they can to save the remaining honeycreepers.

“These are endemic species that are found nowhere else, and they have a very strong connection with the Hawaiian culture, the Hawaiian community,” Paxton said. “This is the health of the Hawaiian forests. And so this has real importance.”

Civil Beat’s coverage of climate change is supported by the Environmental Funders Group of the Hawaii Community Foundation, Marisla Fund of the Hawaii Community Foundation and the Frost Family Foundation.

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