The Mosquito Problem

Ari Daniel: BirdNote Presents.

[Echoing Wingflaps SFX]

[Doorknob rattles; a door creaks open]

Ari Daniel: To enter David Kuhn’s little green cabin is to step back in time.

[Some unidentified birds can be heard in the background]

David Kuhn: I’m supposed to be retired, and so I’m looking for ways to be retired. But I’m not going to retire from recording. I still have good hearing.

Ari Daniel: Kuhn’s been recording birdsong here on the island of Kauai — one of the northernmost islands in the Hawaiian archipelago — since the mid 90’s.

David Kuhn: I remember making the recording, of being there, and experiencing whatever ecosystem I was in.

Ari Daniel: This recording’s from 2005.

David Kuhn: Hear that? That’s characteristic of ‘Akeke‘e.

[David plays a recording of an ‘Akeke‘e]

Ari Daniel: The birds we’re listening to are predominantly honeycreepers — a diverse group that descended from a Eurasian finch three to five million years ago, and that we heard about in our last episode. But in just about the time that David Kuhn has lived on Kauai — some three decades — the honeycreepers endemic to this island have nearly vanished.

David Kuhn: These sounds can bring back memories that are part of my wealth.

[Reflective Threatened theme music begins]

Ari Daniel: The threats to the honeycreepers have stacked up over the years. And we haven’t discussed one of the biggest, which we’re devoting this whole episode to… avian malaria. In fact, some fear it might just push these birds over the edge to extinction. [pause]

But a new solution may just save them from the abyss… if we can keep the birds alive long enough to apply it. This is Threatened. And I’m Ari Daniel.

[Sounds of the Pihea trail fade up with soft walking noises; not many birds can be heard]

Ari Daniel: Hundreds of years ago, it’s said that if you approached any of the Hawaiian islands, you’d hear eruptions — not of volcanoes, but of bird song. In fact, this trail on Kauai that I’m walking along at the moment — a forested ridgeline across a plateau — is called the Pihea trail, which means “cacophony” in Hawaiian.

Cali Crampton: Once upon a time, you couldn’t hear yourself think for the birdsong on this trail. You would look up, you wouldn’t see clouds and blue sky — you would see flocks of birds in a Hawaiian forest.

Ari Daniel: Ecologist Lisa “Cali” Crampton is guiding me on this trail. And she says that when she first arrived here in Kauai 12 years ago, that hubbub had lessened, but there were still places she could camp where the chorus of birdsong jolted her awake in the mornings. However, things aren’t what they used to be.

Cali Crampton: It is just eerily, spookily quiet.

[Hold for a few beats on the silent forest ambi]

Ari Daniel: Cali runs the Kauai Forest Bird Recovery Project. And when she took the job in 2010, there was only one federally endangered species on the island: the Puaiohi, a thrush found here on Kauai and nowhere else in the world.

Cali Crampton: They are the only fruit-eating bird left on Kauai, at least native species. And so fruit eaters are primarily responsible for seed dispersal of fruiting species. So it’s a really important species to forest regeneration. So without the forest, there’s no birds, but without the birds, there’s no forest.

Ari Daniel: While only the Puaiohi was federally endangered when Cali began her new job, she soon got some bad news about two species of honeycreepers, also found only on Kauai. The ‘Akikiki — an acrobatic and vocal little gray bird with a pink bill, and the ‘Akeke‘e — a bright yellow bird with a forked tail, black mask, and crossed beak.

Cali Crampton: The ‘Akikiki populations and the ‘Akeke‘e populations were declining at alarming rates and their ranges were contracting significantly.

At that time, we thought that there were more than a thousand ‘Akikiki, and more than 3000 ‘Akeke‘e. By the time we did the next round of surveys in 2012, only two years later, it became evident that in fact, they were much closer to 500 or even fewer ‘Akikiki and a thousand ‘Akeke‘e.

Ari Daniel: In just a few years, their numbers fell by more than half. These are the birds that we’re in search of on this hike. Cali’s moving at a good clip, but she’s skeptical we’ll see any. Both the ‘Akikiki and the ‘Akeke‘e have been on the endangered species list for over a decade. And the extra protections that listing afforded were pretty much too little, too late to prevent the sudden decline.

Cali Crampton: Nowadays, our reality is vastly different. We believe that there’s not 500 ‘Akikiki, but maybe 50 ‘Akikiki. And not a thousand ‘Akeke‘e, but maybe 700 ‘Akeke‘e.

Ari Daniel: About 700 ‘Akeke‘e and 50 or so ‘Akikiki. The precipitous decline of these birds is due to numerous causes. Clearcutting the forest. Expanding towns and agriculture. Invasive predators like rats, which eat eggs and birds. Invasive flora which cause habitat loss — a process accelerated by other invasive species like feral pigs. And then there’s the thing that seems to have pushed these birds over the edge, across that invisible line where more individuals are disappearing than being born. Cali points to a series of puddles beside the path we’re hiking along — small pools of standing water.

Cali Crampton: So we do sometimes find mosquito larvae in these pools.

[Slightly tense piano music begins]

Ari Daniel: Mosquitos. In particular, the Southern house mosquito. It’s an invasive species that arrived in the 1820s as a stowaway in the water aboard whaling ships. And this mosquito now carries the parasite that causes avian malaria.

Cali Crampton: It’s related to human malaria. It causes the same set of symptoms, but only in birds. And it’s fatal for many Hawaiian honeycreepers who have no evolutionary history with avian malaria. They are naive to this disease, just the way we were naive to COVID. And it has had dramatic consequences for the honeycreeper species the way COVID has had dramatic consequences for human populations.

Ari Daniel: Avian malaria probably began to spread in earnest in the early 1900s. Mosquitos bite the birds anywhere that’s unfeathered — the beak, legs, and… the eyes. It’s affected a variety of birds, but more recently, the honeycreepers have been hit especially hard.

Cali Crampton: mosquitos mostly like it where it’s warm and humid. So they kind of just simmered at low elevations around the coasts of the Hawaiian islands for a very long time.

Ari Daniel: Which wiped out the birds at lower elevations. But climate change has warmed the islands and created more standing water. Which has opened up new habitat for the mosquitos at higher elevations. And so the insects have advanced farther and farther upslope, into the remaining honeycreeper refuges. And avian malaria is now decimating these birds, too.

Which is why finding a solution to avian malaria has been the focus of intensive research for the last 30-some years.

[Tense piano music fades out]

[Door thumps shut; sound of fans and humming equipment can be heard in the lab]

Dennis LaPointe: It’s a little warmer in here.

Ari tape: Oh yeah, it’s a little toasty. What do you keep it at? 80?

Dennis LaPointe: We try to, yeah, just about 80.

Ari Daniel: Research ecologist Dennis LaPointe is an entomologist by training, and has done a variety of experiments on the mosquitos in his lab here.

Dennis LaPointe: They’re fascinating insects. It’s a love-hate relationship, there’s no question about it.

Ari Daniel: While Cali has dedicated her life to the honeycreepers to save them, Dennis has devoted much of his to these mosquitos… to destroy them. He shows me his mosquito rearing room at the USGS Pacific Island Ecosystems Research Center. It’s located on the Big Island, inside Hawaii Volcanoes National Park. We gaze into a jar half-filled with murky water and mosquito larvae darting about.

Ari tape: So these are the culprits.

Dennis LaPointe: These are the culprits, as babies. They’re still innocent. They’re quite small at this point.

Ari Daniel: As the forests of Kauai have steadily emptied, a new possible solution in the battle against avian malaria has slowly taken shape over the last 25 years. It’s called Wolbachia. It’s a variation on something called the “sterile insect technique.” Dennis takes me outside to elaborate.

[Lab sounds fade out; some birdsong can be heard outside the lab]

Dennis LaPointe: The whole idea is to take a male of the insect that you want to reduce in the wild.

Ari Daniel: You raise vast quantities of them in the lab, and then you sterilize them with radiation or chemicals. So when they mate with the wild females, the result is huge numbers of eggs that will never hatch…

Dennis LaPointe: If you do this successively over time, you can suppress the population.

Ari Daniel: But in the case of the Southern house mosquito, this technique not only sterilizes them, it also knocks their mating behavior off kilter. They can’t compete with the fertile males. So Dennis and a team of researchers changed course, turning their attention to a different means of achieving sterilization. That’s where Wolbachia comes in. It’s a bacterium that lives in the reproductive tracts of numerous insects, including the Southern house mosquito.

Dennis LaPointe: It can cause a breakdown in reproduction and it’s called cytoplasmic incompatibility. So there are variants in this bacteria from one population to another.

Ari Daniel: And for reasons that aren’t entirely evident, sometimes when a male mosquito has one kind of Wolbachia and a female mosquito has a different kind — they won’t be able to reproduce. The eggs won’t hatch. So Dennis and his colleagues, across a variety of agencies, under the name “Birds, Not Mosquitos…”

Dennis LaPointe: Gets to the point.

Ari Daniel: …are going to release males with Wolbachia into the wild. But for this approach to be effective, to crater the Southern house mosquito population, the researchers need to flood a place like Kauai with these males, and that’s challenging.

Dennis LaPointe: How do you get all those mosquitoes out there? Currently programs that are attempting to do this in Australia and Fresno, California, they’re able to drive through communities and release the mosquitoes out of the back of a van. We won’t have that luxury. So we’re either going to be hiking these mosquitoes in by the hundreds of thousands and releasing them in the field, or we’re going to have to develop aerial techniques for that release.

Ari Daniel: And to succeed, they’ll have to do these releases again and again to knock the mosquito numbers back to near zero. So it’s no slam dunk, plus there are still some regulatory and funding hurdles, and there’s always some risk involved with a plan like this.

Ari tape: So, you know, there’s a long history in Hawaii of bringing things in that then create problems. Feral pigs…

Dennis LaPointe: Right.

Ari tape: Mongoose…

Dennis LaPointe: That’s definitely a concern…

Ari tape: Rats.

Dennis LaPointe: …when you do something like this. But these are still valuable tools provided the regulations were put in place and people proceed cautiously.

Ari tape: So you feel that there’s minimal, if any risk.

Dennis LaPointe: I don’t know if I should be saying there is no risk. But I think the “Birds, Not Mosquitos” group is convinced that the risks are fairly minimal.

Ari tape: And the potential payoff.

Dennis LaPointe: Of course, the potential payoff is phenomenal. We really are stuck at this point. We don’t have a tool. This is the first tool that’s come along that doesn’t send up red flags everywhere. And so we think it’s worth pursuing. So I’m cautiously optimistic. 

[Tense string music begins]

Ari Daniel: A new infusion of federal funds adds to that optimism. A solution is desperately needed, and has been for decades. But it’s still not ready yet. And the honeycreepers may not be able to wait. So Cali and her team are working to buy them a little more time. How they’re doing it, after the break.

[String music fades out]

[MIDROLL AD BREAK]

[Sounds of Pihea trail fade up; some more birds can be heard now; there are soft footsteps as Ari and Cali walk along]

Ari Daniel: Back on the Pihea trail on Kauai, this is where that carousel of bird, bug, and parasite has cycled over and over again, with devastating results. Added, of course, to all the other threats. To keep the Kauai honeycreeper numbers from falling further due to avian malaria, ecologist Cali Crampton and her team ushered in a multi-pronged offense. Including one effort that was especially bad ass. Collecting eggs. I know, that may not sound heroic, but trust me. What follows is something out of a heist movie — but with the noblest of motives.

Cali Crampton: Yeah, it was a pretty epic undertaking. And this is an endangered species. And if you knock the nest out of the tree of an endangered species, you could imagine everything would be shut down.

Ari Daniel: So: super delicate — a process requiring five to seven people. The idea was that once they had the eggs, they’d hatch them in captivity and raise the malaria-free birds in a protected environment, giving the species an insurance population in case their parents crashed out completely in the wild. For the honeycreepers, once the eggs were removed, it often motivated the birds to re-lay. The ‘Akikiki usually produce two eggs, the ‘Akeke‘e two to four, and each egg weighs about a bit less than a blueberry.

Cali Crampton: They’re tiny. They’re tiny, little eggs. And so we partnered with San Diego Zoo Wildlife Alliance because they are experts in handling these tiny, little eggs. And when the eggs were about eight to 12 days old, so the embryo was fairly developed, but not in danger of hatching, we would target it for collection.

Ari Daniel: Which meant everything was arranged last minute. Find a nest, make sure the eggs are the right age — 8 to 12 days old, and, if so… 

[Energetic heist music begins]

…launch the chopper.

Cali Crampton: We would fly a hundred-pound, 40-foot extension ladder into a clearing in the forest a couple hundred meters from the nest. 

Ari Daniel: They wanted to be far enough away so the nest wouldn’t be disturbed.

Cali Crampton: And we would drop the ladder through the forest on a line from the belly of the helicopter and then hike it to the nest.

And then we had to figure out how to position the ladder about a foot away from the nest at nest height suspended by really, really strong ropes that were lashed off to trees.

Ari tape: So it’s free-standing.

Cali Crampton: It’s a free-standing ladder. So it has two feet on the ground. You can imagine that this a hundred pound ladder, in a tight forest clearing, often tighter than the one we’re in right now. 

Ari Daniel: The ladder needed to reach nests that were about as high up as a 3- or 4-story building.

Cali Crampton: And then once it was in place, put a harness on the climber, put a harness on somebody on the ground, belay the climber, like you would for rock climbing, just in case something happened with the ladder or they slipped or whatever, they would not fall to the ground.

Ari Daniel: And despite all this commotion, there’d be a tiny female, weighing about as much as a triple A battery, holding strong, sitting on her nest to keep her blueberry eggs safe.

Cali Crampton: She would frequently just sit there until the climber was halfway up the ladder. And up they went to the nest to reach in and grab these tiny little eggs.

[Heist music ends on an organ chord and rattling percussion]

Ari Daniel: They’d carry one of those wide-mouthed thermoses filled with prewarmed millet — think roasted couscous.

Cali Crampton: They would open the lid of the thermos, extract a cup of millet, take it to the nest so that they could basically position the eggs directly into the little cup of millet. 

And then once they had both eggs nestled in the millet, they would gingerly put that back in the thermos, screw the lid of the thermos tight, and lower it to the ground on a rope where it would be caught by somebody at the bottom of the ladder.

Ari Daniel: That cup of millet would be transferred to a small cooler retrofitted with a little heater powered by six-volt motorcycle batteries to keep the eggs warm. Then, they’d strap it on to something like a fanny pack.

Cali Crampton: And we would slowly hike our way through the forest, often be up and down. We’d have to pass the cooler up the hill to each other as we all scampered up. 

Ari Daniel: They’d get into the waiting helicopter, then fly to a breeding incubating center… just in time. Because if they clocked it right, only two to six days later, the eggs would hatch.

Cali Crampton: And then they would feed them until about the time the eyes open, maybe eight or 10 days, and fly them in a small cage on Hawaiian Airlines to the conservation breeding facility on Maui.

Ari Daniel: Like I said, bad ass. Cali and her team managed to collect eggs from 32 ‘Akikiki nests and a dozen ‘Akeke‘e nests. From 2015-2018, this dominated Cali’s life. And yet, despite these heroic and intensive efforts, the declines continued. 

[Somber ukulele music begins] 

After about an hour and a half of hiking, Cali finally stops. The past and present flicker before her.

Cali Crampton: It has been 10 years since I saw a Puaiohi in this area. And eight since I saw an ‘Akikiki. They have just receded and receded and receded.

Ari tape: So you’re saying where we’re standing now is kind of looking into the future?

Cali Crampton: Yeah. What we have seen here, starting 10 years ago is now happening in the last three to five years deeper in the range. So at the bastion of the ‘Akikiki population, we have gone from probably close to a hundred birds in 2015 to only four birds last December.

Ari Daniel: The word “freefall” comes to mind. A hundred birds to just four in the heart of ‘Akikiki habitat. It’s a devastating loss for Cali and the researchers she works with.

Cali Crampton: For my team, my team that’s out there every day working with the birds, they know the birds by these colored bands, bracelets they have on their legs. Or by their plumage or by the territory they normally hold. 

They’re saying goodbye to almost friends. Like there is no ‘Akikiki greeting you in the morning anymore. And that bird, one of those birds was there for years. We knew it.

 It’s like going and knocking at the door and no one’s home. Like the plague, right, when houses were emptied in Europe. 

So, you know, there are moments of overwhelming sadness because we haven’t been able to do enough yet.

Ari Daniel: It was in the midst of this sadness that Cali reached out to a woman named Keahi Manea.

[Somber ukulele music fades out]

Keahi Manea: You know, it was such a personal thing. It’s like they wanted to share it with somebody outside themselves. Somebody that doesn’t go into the forest, like they do. 

Ari Daniel: Keahi, who’s 79, spoke to me at a park on the east coast of Kauai. Since 2011, Cali has invited Keahi and her group to bless the research season through special songs, prayers, and invocations of the ancestors and Hawaiian deities. A kind of sanctification of the science.

Keahi Manea: I'm a member of Ka’Imi Na’auao O Hawai’i Nei Institute, which is a cultural institute established in the late 70’s with hula as our educational base.

Ari tape: And what is hula?

Keahi Manea: Dance. It means “to dance.”

Ari Daniel: Last year, Cali told Keahi that their grief had grown too great to keep it to themselves. She and her research team invited Keahi’s group to one of the honeycreeper field sites to talk about their feelings of loss.

Keahi Manea: We went up there on a rainy day. And they told us about not being able to find birds that they had names for. They couldn’t find them, they were gone. We’re losing them so fast. That particular outing with Cali and her staff really was touching.

Ari Daniel: Here’s Cali again.

Cali Crampton: She thought about it long and hard and about how, what would be appropriate in Hawaiian tradition. She composed a little ceremony for us, my staff attended, and they spoke their thoughts, and we spoke our thoughts. And we chanted “auē,” which is “alas.” But it was just an opportunity for us to share how, what a bummer! What a bummer that all our hard efforts are, weren’t working and our fears…

Keahi Manea: We didn’t do anything. We didn’t… we sang. After everybody said what they wanted to say and we talked about it, we reassured them: “What more can you do? You’re doing all you can you do? You’re getting in helicopters. You’re dropping down into this remote forest in the rain. What more can you do? You’re doing all you can. So go ahead and be sad if you want to be sad. 

Cali Crampton: All this was cooped up and she let us let off the steam and shed our feelings. It was great.

Keahi Manea: Just comforting somebody that’s telling you that they’re feeling a loss. That’s all it was. It was their bird family.

Ari tape: It also strikes me that you were there to bear witness.

Keahi Manea: Yes, so yes, that’s a good way to put it. Exactly. Yeah, it was like a eulogy or like a funeral.

Ari Daniel: A eulogy or a funeral for so many individual birds— but not yet for an entire species. Because this solution to avian malaria — Wolbachia — is so close. And everyone I spoke to wanted it, like, yesterday. Keahi chief among them.

Keahi Manea: Hallelujah. Go for it. Do it. They can’t do it soon enough. If the scientists trust it, and have studied it, and believe that it’s the way to go, then do it.  Mosquitos aren’t native to Hawaii. Come on.

Ari tape: So you’re all for gettin’ rid of ‘em.

Keahi Manea: Exactly, execution, yeah.

Ari Daniel: The hope is the Wolbachia mosquitos will be ready for release in two to three years. That timeline’s probably okay for the ‘Akeke‘e. But not for the ‘Akikiki. Cali Crampton told me that without intervention, they’re likely to be extinct by early 2023.

Cali Crampton: We’ve decided that the most prudent thing to do is bring more of them into conservation breeding until such a time, a couple of years later, hopefully as Wolbachia is available on the landscape, controlling mosquitoes and just release birds back into the wild. So it’s more like maybe even a holding, right?

Ari tape: You mean like bring the malaria under control with the Wolbachia…

Cali Crampton: And then once malaria’s under control with the Wolbachia, we can release birds back into the wild. We’re just keeping them safe, right? Like a bomb shelter, right? Like keeping things safe.

Ari Daniel: Ever since the day she showed up for work on Kauai, there’s been a downward trajectory of these birds. But Cali is heartened by the promise of Wolbachia, combined with other conservation measures currently in place.

Cali Crampton: So we hope that once the Wolbachia landscape level mosquito control is available, not only will we arrest the declines of ‘Akikiki, and ‘Akeke‘e, we may be even able to start seeing them repopulate areas and their populations increase because the habitat will be in good shape and ready to be filled by these birds.

Ari Daniel: All these efforts — helicoptering in ladders to collect the honeycreeper eggs, poring over the perfect way to sterilize mosquitos — these are the extraordinary options we’re left with to save the honeycreepers. All because we’re not reducing our emissions. For that’s what’s opened up the higher elevations to the mosquitos to begin with. Still, the final chapter has not yet been written. 

Cali Crampton: I have to keep assuming that there is a way because the minute you give up, there is no way.

Ari Daniel: Perhaps, one day, before Cali retires, she’ll come to the forests and hear the raucous chorus of her friends once again. 

[Reflective Threatened theme music begins to fade in]

And as for that hike on the Pihea Trail, I never saw a single  ‘Akikiki or ‘Akeke‘e.

[Threatened theme soloed for a few seconds]

In Hawai‘i our current extinction crisis is a stark reality. Two-thirds of the birds here have gone extinct since humans first set foot on the islands. Some are lost forever and we’ll never know them. But some are still with us, in a way. 

CP: Stories are our memories in many ways. And so, you know, stories about birds or other lost species help keep them alive in our imagination.

Next week on Threatened, the story of one such bird and its role in the royal lineage of the Kingdom of Hawai‘i.

This episode was produced by me, Ari Daniel. It was edited by Caitlin Pierce of the Rough Cut Collective. Audio mix by Sam Johnson and Mark Bramhill. Fact-checking by Conor Gearin. Our theme song and original music were composed by Ian Coss, with additional music by Blue Dot Sessions and Sam Johnson. Threatened is a production of BirdNote and overseen by Content Director Allison Wilson. You can find a transcript of this show and additional resources, BirdNote’s other podcasts, and much more at BirdNote dot org. Thanks for listening. See you next time.

[Threatened Theme ends]

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SFX:

Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. 

MUSIC:

Threatened Theme by Ian Coss

“Heist” by Sam Johnson

“Clatl”, “Douglass Stairs”, and “Wahre” by Blue Dot Sessions