MARY LOUISE KELLY, HOST:
More species have gone extinct in Hawaii than any other state. Several Hawaiian birds known as honeycreepers are on the brink of joining that list. The problem is mosquitoes, which transmit lethal avian malaria. So wildlife officials are trying an unusual solution - adding more mosquitoes. NPR's Lauren Sommer reports from Maui.
LAUREN SOMMER, BYLINE: When a wildfire hits, a lot of people think about what they can save. For Jennifer Pribble, it was saving an entire species from going extinct.
JENNIFER PRIBBLE: I didn't know that there was a fire until 3:00 a.m.
SOMMER: This was one of the fires that hit Maui in August last year, and Pribble works at the Maui Bird Conservation Center, home to some of the rarest birds in the world. So when the fire came across the street...
PRIBBLE: Then I had fire extinguishers and garden hoses and put the fire out. So, yeah, that was a long night.
SOMMER: She was protecting the enclosures here, tucked among the trees each with a highly endangered bird.
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SOMMER: There's the alala, the Hawaiian crow, which is extinct in the wild. And in another enclosure...
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SOMMER: Oh, yeah, there he is.
A tiny, pale gray bird hopping from branch to branch. It's the 'akikiki. Its population has plummeted.
PRIBBLE: Fifteen years ago, the population was over a thousand. And today, there's anywhere from two to five birds left in the wild.
SOMMER: That means this bird will likely go extinct in the wild sometime this year. Several dozen 'akikiki have been brought here to protect what's left.
PRIBBLE: We call our program kind of an intensive care unit. This is the last resort.
SOMMER: Pribble says they're working on a breeding program, trying to grow the numbers of these birds. But right now they can't release them back to the wild because inside these walls is the only place that's safe.
PRIBBLE: All of our aviaries are free of mosquitoes. So we have a mosquito screen that wraps all of our aviary buildings.
SOMMER: Outside in the forest, birds can die after a single mosquito bite. Christa Seidl is walking through one of those forests.
CHRISTA SEIDL: Oh, actually, I just heard a Hawaii 'amakihi.
SOMMER: She works at the Maui Forest Bird Recovery Project, a nonprofit that's trying to help honeycreepers hang on. And we do hear one.
SEIDL: He's probably, like, right up here.
SOMMER: But this forest is quiet. You barely hear any birds.
SEIDL: Before mosquitoes and before disease, this forest would be a cacophony of birdsong. And there would be huge flocks of 'i'iwi and 'apapane.
SOMMER: There were once more than 50 species of Hawaiian honeycreepers. They were red and yellow and lived in the native forests. But now only 17 species are left. Many of their forests were cut down for farming and ranching. Invasive plants and animals took over. And in the 1800s, mosquitoes were brought in, probably on a ship. Those mosquitoes spread avian malaria, and the native birds had no resistance. Honeycreepers began disappearing.
SEIDL: This is an incredible animal that exists nowhere else, and it has a valuable ecosystem role here in Hawaii.
SOMMER: Honeycreepers pollinate flowers and support the entire forest. They're also important in Native Hawaiian culture. But there are forests on Maui that still sound like they once did.
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SOMMER: That is a patch of forest at higher elevation on Maui. Above four to 5,000 feet, it's been too cold for mosquitoes, So the birds there survived. But then came climate change.
SEIDL: It's increasing in temperature, and that's allowing mosquitoes to creep increasingly up slope.
SOMMER: Seidl and her colleagues have watched this happen in real time. They've been trying to save another honeycreeper that's on the brink, the kiwikiu, a yellow bird with a parrotlike beak.
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SOMMER: So they spent a decade restoring a native forest for them where there were no mosquitoes, planting tens of thousands of trees. Then Seidl's colleague Hanna Mounce released some birds.
HANNA MOUNCE: Tragically, the landscape had basically shifted under our feet. And the birds that we translocated - all but one died within a few weeks.
SOMMER: Mosquitoes had moved in because of a heat wave, so the birds were lost.
MOUNCE: I mean, when failure is extinction - and, you know, we want to know that we've done every single thing that we possibly can.
SOMMER: It seemed hopeless. With climate change, the old playbook for saving endangered species just wasn't enough. But then a new idea came up, one that's been used to protect humans.
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SOMMER: At the Maui airport, Seidl is loading up some very special cargo.
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SEIDL: So here's one of the pods.
SOMMER: It's a cardboard tube with a plastic lid.
SEIDL: So inside is about a thousand male mosquitoes.
SOMMER: In all, about 250,000 mosquitoes here are boarding a helicopter. They're being flown to the mountains where endangered birds live and then airdropped. To stop mosquitoes, Seidl and her colleagues are releasing more mosquitoes. But these ones have been altered. They're all male, which means they don't bite people or birds. And when they mate with females, they're not compatible. They've been given a naturally occurring bacteria that interferes with reproduction.
SEIDL: So we're really hoping most of these wild females are going to encounter one of our males, and thus all of their eggs won't hatch.
SOMMER: And if you get enough mosquito couples who can't reproduce, the mosquito population starts to fall.
SEIDL: This technique has been used all over the world to reduce mosquito populations. They've used it successfully in China, in Mexico. There's programs ongoing in California, Florida.
SOMMER: Those programs are to stop the spread of human diseases like dengue, but this is one of the first times it will be used for wildlife conservation. Chris Warren of the National Park Service is also working on the project since the mosquitoes will be released in Haleakala National Park.
CHRIS WARREN: What the previous studies have really shown is that this tool works, but the biggest issues with this is, can we apply the tool effectively enough to reduce the mosquito population?
SOMMER: Mosquitoes need to be released twice per week in very remote places, and it has to be ongoing to keep the population in check, which means the National Park Service will need to keep finding the funding. It's a sign of how much farther humans are having to intervene to save the biodiversity that's left. Warren says they're hopeful this project will work, but time is running out for the birds.
WARREN: If you're in the conservation business, you are an optimist. You know, the only thing more tragic than these things going extinct would be them going extinct and we didn't try to stop it.
SOMMER: There's no getting rid of mosquitoes in Maui completely. But the idea is that eventually, Hawaii's honeycreepers could develop immunity to avian malaria, just as other birds have. And there has been a promising sign. One kiwikiu that was released didn't die from malaria. Hanna Mounce says he just reappeared out of the blue.
MOUNCE: I don't know how he did that, but he not only survived malaria. He had a successful hatcher, fledged a chick last year, and he has a female this year. He's doing great.
SOMMER: She says it's a sign honeycreepers could develop enough immunity to survive. They just need to stay alive long enough to do it. Lauren Sommer, NPR News.
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