EMILY KWONG, HOST:
You're listening to SHORT WAVE...
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KWONG: ...From NPR.
Hey, SHORT WAVErs. Emily Kwong here. There is an extinction crisis underway on the planet we call home. Animals and plant species are rapidly disappearing. And people all over the world are going to increasing lengths to save them, doing things like...
LAUREN SOMMER, BYLINE: Packing a helicopter full of 250,000 mosquitoes.
KWONG: Not the conservation strategy I had in mind, but OK. Lauren Sommer, you and Ryan Kellman are here from the climate desk to talk about this practice. What is up with this helicopter full of mosquitoes?
RYAN KELLMAN, BYLINE: Yeah, don't worry Emily. They're not just flying around loose in the cockpit. They're packed away in little, brown tubes that kind of look like toilet paper tubes.
SOMMER: They're actually heading out to the high mountain forests of Haleakala National Park, where they'll be released to ultimately help endangered birds.
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KELLMAN: So that's an i'iwi. It's got a bright, red body, with a black tail and black wings and a pink beak that curves downward. It's a very cool bird.
KWONG: Aw.
KELLMAN: And Lauren and I got to see these birds not too far from where the mosquitoes were dropped.
SOMMER: Yeah, and the i'iwi is one of Hawaii's honeycreepers. They're these small birds that are found nowhere else on the planet. There used to be more than 50 species of honeycreepers, but now there are just 17, and several of those are very close to extinction in the wild.
KWONG: I've heard of these birds. Honeycreepers - they're so important to Hawaii's ecosystem, to the people. But how are, like, mosquitoes connected to these birds?
SOMMER: Mosquitoes are not native to Hawaii. They were introduced by accident...
KWONG: OK.
SOMMER: ...Probably. And they carry avian malaria. Honeycreepers have...
KWONG: Oh.
SOMMER: ...No immunity to it, so they can die after a single mosquito bite.
KELLMAN: And obviously, it would be incredibly hard to get rid of all the mosquitoes on Maui. But they're trying to at least control them. And that's where the helicopter comes in. They're releasing special mosquitoes - ones that can't reproduce with the mosquitoes already on Maui.
KWONG: OK, let me get this right. You're saying the plan is to stop mosquitoes from killing honeycreepers by releasing more mosquitoes.
KELLMAN: Right.
SOMMER: Exactly. It's a technique to suppress their population.
KWONG: Huh.
SOMMER: And it's been used elsewhere in the world for human health reasons - you know, to sop diseases that we get from spreading.
KWONG: OK.
SOMMER: But this is really the first time it's been used for wildlife conservation, and the big question is whether it can make a difference in time to save these birds.
KWONG: So today on the show, a race against time to try to save some of the rarest birds on Earth - how scientists are innovating in the world of conservation to save species from extinction. You're listening to SHORT WAVE, the science podcast from NPR.
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KWONG: OK. So Ryan Kellman, Lauren Sommer, you went to the island of Maui to report on these birds that are disappearing. How soon do we think honeycreepers are going to go extinct?
SOMMER: Yeah, for some honeycreepers, it could be a matter of years, and so that's why they're bringing some of the birds into captivity - as a way of protecting them.
KELLMAN: We got to see some of these birds at the Maui Bird Conservation Center, which is a very cool place - particularly if you're a bird nerd - with a whole bunch of bird enclosures.
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SOMMER: So that's the 'alala, the Hawaiian crow. It's totally extinct in the wild now.
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KWONG: Oh, this guy - he's got things to say. All right.
KELLMAN: Yeah - very chatty bird.
SOMMER: Jennifer Pribble is the wildlife care supervisor at the center, and she showed us around.
JENNIFER PRIBBLE: If we do have a pair of birds, they'll get two compartments where they can kind of interact with each other. But they also have the option to get away from their mate if they need to.
KWONG: How, considerate. OK. So these folks at the conservation center are taking care of these birds. Is the idea to, like, safeguard the birds for now and just keep the population going?
KELLMAN: Yeah. It's definitely a last resort. Jennifer actually lives at the facility. And when those devastating wildfires hit Maui last August, one got really close.
SOMMER: Yeah, at 3 a.m., she said it was right across the street, so she jumped into action.
PRIBBLE: I had fire extinguishers and garden hoses and put the fire out. So yeah, that was a long night.
KWONG: Wow. I mean, so while some people were, like, saving their homes or photo albums or keepsakes, Jennifer was trying to save this whole facility and, really, the species that were inside.
SOMMER: Yeah. Yeah. I mean, I should say there is another facility where the birds are kept, too, just in case something like a fire happens. But each bird is valuable because there are just so few remaining.
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SOMMER: Like in another enclosure...
Oh yeah, there he is.
...There was a tiny, pale gray bird called the 'akikiki.
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PRIBBLE: Fifteen years ago, the population was over a thousand.
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SOMMER: Wow.
PRIBBLE: And today, there's anywhere from two to five birds left in the wild.
KELLMAN: That bird species will probably go extinct in the wild sometime this year.
KWONG: Wow. These are very precious birds, you know?
KELLMAN: Yeah, it's why they have a breeding program at the center.
PRIBBLE: Yep. And we do have a nest right down here.
SOMMER: She says maybe three to four 'akikiki hatch a year. But even if they can grow the numbers of those birds, they can't release them into the wild because outside these walls are mosquitoes.
KWONG: OK, so because of this mosquito situation, are the birds kind of marooned in human care?
KELLMAN: Yeah, exactly. It's a real, like, island-within-the-island-situation.
KWONG: Yeah.
KELLMAN: But there are some really dedicated people trying to change that - to get the birds back into the wild. One of those people is Christa Seidl. She works with the Maui Forest Bird Recovery Project, and we met up with her in a forest where she kept on trying to find birds for us.
CHRISTA SEIDL: I just heard a Hawai'i 'amakihi.
SOMMER: Yeah. It was actually really quiet.
SEIDL: I'll listen for it again.
SOMMER: And that forest really showed how Maui has changed. You know, much of the native forest was cut down for farming and ranching. And where we were, it was kind of full of these invasive plants like ginger, which was really choking everything else out. And the native birds have mostly disappeared.
SEIDL: So 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: But there are places on Maui where you can still find that.
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KWONG: Oh, that's gorgeous. It's amazing to hear that difference. So OK, where was this recorded, and what's different about this forest?
SOMMER: Yeah, so that's a forest at higher elevation on Maui because, above four- to 5,000 feet, it's actually been too cold for mosquitoes to live there, so the birds have survived. But - yeah, there's a but here - then came climate change.
SEIDL: It's increasing in temperature, and that's allowing mosquitoes to creep increasingly upslope and now invade habitats that were once the last remaining refugia for a lot of our native birds.
KWONG: OK. So these spots that were once safe for birds are now home to, like, creeping mosquitoes. And, of course, all this is being accelerated by the way humans are heating up the planet.
KELLMAN: Right. Exactly. And Christa and her colleagues have had to actually watch this happen in real time. For example, they've been trying to save another honeycreeper that's on the brink of extinction, called the kiwikiu.
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KELLMAN: And it's a cute, little, yellow and olive-green bird with a sort of parrotlike beak.
KWONG: Nice.
KELLMAN: One problem was that there wasn't enough habitat for them, so they started restoring a forest.
SOMMER: They planted tens of thousands of trees at higher elevation to create a safe place for the kiwikiu. It took a decade. And Hanna Mounce, who also works with the Maui Forest Bird Recovery Project, told us that, you know, after all that preparation, they finally released some birds in 2019. But...
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: Weeks?
MOUNCE: It was bad. It was really bad.
KWONG: That's so sad. What happened?
KELLMAN: Yeah, so the problem was it had been really hot, and that warm weather allowed the mosquitoes to move in. So almost all of the birds were lost to avian malaria that they got from those mosquitoes.
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, even if we don't - if we do end up losing some of these species, it's still incredibly difficult.
KWONG: I mean, how do you even bounce back from something like that - like, after all that work, when the stakes are so high?
SOMMER: Yeah. Yeah. I mean, we definitely asked her that because it's a lot to have the fate of an entire species in your hands.
KWONG: Yeah.
SOMMER: And she said it felt really hopeless until this idea of releasing mosquitoes came up.
KWONG: OK. This surprises me 'cause, so far in this story, like, I'm not feeling these mosquitoes. They sound quite villainous. But, like, how is adding mosquitoes a form of population control? How in the world does that work?
KELLMAN: Here's the thing - the mosquitoes being released are all males, and the males don't bite humans or birds. It's actually only the females that drink blood. Anyway, they've been altered in a way where they can't reproduce successfully with the female mosquitoes. The eggs aren't viable. And those female mosquitoes only mate once, so you've effectively taken them out of the game.
KWONG: How do scientists, like, get the males to be nonviable anyway?
SOMMER: Yeah, it's actually interesting. So you and I - we both have bacteria living inside us, right? Mosquitoes are like us, too. They have bacteria. One of them is called Wolbachia, and it can actually modify the reproductive cells in mosquitoes. So if a male and female have the same strain of this bacteria, they can make babies. If they have different strains, no babies.
KWONG: That is some really powerful bacteria.
KELLMAN: It is very powerful. And Christa says this method was developed to suppress mosquitoes that spread human diseases like dengue.
SEIDL: So 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.
KWONG: OK, and now they're trying it out in Hawaii. That's cool. So if enough mosquito couples do not have offspring, the population goes down. But what does it take, Lauren, to, like, keep it that way and make that a permanent reality?
SOMMER: Yeah. You have to keep releasing these male mosquitoes to keep the population down.
KWONG: Gotcha.
SOMMER: And I talked to Chris Warren about this. He works on this project at 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: And so far they have released 10 million of those male mosquitoes, and they're watching to see if the overall mosquito numbers start to fall soon.
KWONG: But given, like, the challenges they've had before with conservation efforts, how hopeful are they that this will work?
SOMMER: You know, honestly, I think, for people like Chris, who work on this and have worked on it so long, the only choice is to be hopeful.
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: And, you know, it really shows that the old way of saving species just may not be enough anymore. You know, that was where you kind of restore their habitat and release animals and help their population grow. Now, it's really taking this new technology and new ways of intervening just to keep up with how fast wildlife is disappearing with climate change.
KWONG: Yeah, this really does subvert, like, all my ideas about how conservation happens. And I guess I just am thinking a little bit about the ethics of it all - like, how far should we as humans go to save species?
KELLMAN: Yeah. And Lauren and I - we've talked to a lot of people about this.
KWONG: Yeah.
KELLMAN: And, you know, we ask that question all the time as we do our reporting - like, what is the value of a single species?
KWONG: Yeah.
KELLMAN: And, of course, there's a biodiversity argument. These birds help pollinate native trees and support a whole forest ecosystem, and those forests help filter the rainfall that gives Maui residents their water supply - so super important.
KWONG: Yeah. I hear that.
KELLMAN: But for Christa, it was even more than that.
SEIDL: Our world will just become less colorful, less diverse as we continue to let species go extinct.
SOMMER: Yeah, and we heard the same thing from Chris, too.
WARREN: Knowing that these things exist on the planet, knowing that they add that diversity, that little bit of interesting to the planet, you know? - if we lose kiwikiu, for instance, we are all poorer for it, whether we know it or not.
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SOMMER: You know, just to kind of have a hopeful note here - remember the kiwikiu that were released, and, you know, all of them died, but one made it?
KWONG: Yeah.
SOMMER: So Hanna told me he turned up again, totally unexpectedly...
KWONG: Wow.
SOMMER: ...On the other side of Maui.
MOUNCE: I don't know how he did that, but he not only survived malaria. He made it all the way back over the windward side of the island, and he's had - he had a successful hatcher -fledged a chick last year. And he has a female this year. He's doing great.
SOMMER: And, you know, that's a big deal - not only just as kind of a moment of hope that keeps people going, but it's that that bird survived malaria. And the hope is that all these honeycreepers...
KWONG: Yeah.
SOMMER: ...Will develop a resistance to it eventually, as birds have done in other places. So it's really just a matter of buying them enough time to let that happen.
KWONG: Lauren Sommer and Ryan Kellman - thank you for taking us on this journey.
KELLMAN: Thanks, Emily.
SOMMER: Yeah, thanks.
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KWONG: This episode was produced by Hannah Chinn. It was edited by our showrunner, Rebecca Ramirez, and fact-checked by Lauren and Ryan. Gilly Moon was the audio engineer. Beth Donovan is our senior director, and Colin Campbell is our senior vice president of podcasting strategy. I'm Emily Kwong. Thank you for listening to SHORT WAVE, the science podcast from NPR.
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