The sound of silence

By: Eunica Escalante
Images By: Lea Strenge

26 September 2019

“When I first arrived on Kauaʻi in 1988, one could sit right here and hear most of the native forest birds,” says David Kuhn, motioning his hand toward the lush forest that surrounds us. “That time,” he continued, “sadly is long since.”

We are standing in the middle of Kōkeʻe Campground, a state park in Kauaʻi nestled along the edge of Waimea Canyon. When Kuhn first moved to Kauaʻi from his native California, he marvelled at its roadless wilderness: acres and acres of forests, like those at Kōkeʻe State Park, left practically undisturbed. “A lot of this island is uninhabited,” Kuhn says, “a lot of quiet places.”

Quiet places where he, as a bird watcher and nature recordist, could explore and become immersed. Kuhn grew up in California’s San Joaquin Valley, surrounded by a marshland teeming with wildlife. His earliest memories were of studying the birds that frequented the outskirts of the marsh, slowly growing his understanding of various avian species. “The deepest part of birding in me started then,” Kuhn said.

By the time that he got to Kauaʻi, Kuhn had been a bird guide for 19 years. In Hawaiʻi, he expanded his knowledge. At first, he says, he only knew of the Hawaiʻi birds found in the Roger Tory Peterson guides. Yet, after many sessions of exploring Kauaʻi’s forests, Kuhn came to know every one of its rare birds. Today, he’s known as the Bird Man of Kauaʻi, the primer on Hawaiʻi’s most elusive birds. 


“Through years of learning and observing,” Kuhn says, “I can identify most every sound, in Kauaʻi at least.” To this effect, he trails off after his sentence, growing silent until all I can hear are the soft chirps of the birds hidden deep with the forest. Kuhn does this often throughout our interview, stopping mid-sentence and cocking his head to one side, analyzing a specific trill or melody. Then, after a beat, he’ll come to a conclusion: “That’s a huamei,” he’ll exclaim or “Hear that? That’s an ʻapapane.” He can identify birds just by the mere sound of them, which is the bird watching equivalent of knowing them on a first name basis.


So when, about ten years ago while out in the field, Kuhn heard a kokeʻe singing the song of another species, he got worried. “I though I was losing my field skills!” he says. The kokeʻe, a species of Hawaiian Honeycreeper endemic to Kauaʻi, had flown above his head, mimicing the songs of all other native birds: akikiki, amakihi, and ʻanianiau. Up until that time, Kuhn says, he had no idea that these birds could mimic each other, much less hear it happening in the wild.

 
“That was my first graphic inkling that this,” he says, “was something different.”

 

Sometime between 7.2 million and 5.8 million years ago, an ancestor of the rosefinch, a Eurasian bird species, landed on the Hawaiian Islands. No one knows for sure how they got here. Perhaps it sailed across the vast Pacific on a piece of driftwood or was blown into the middle of the ocean by strong winds. What has been widely recorded, however, is the remarkably diverse evolutionary tree that sprang up in its wake. 


Through adaptive radiation, the rosefinch’s descendants evolved to fill the various niches found throughout the Hawaiian Islands, giving rise to the honeycreeper species that once dominated Hawaiʻi’s forests. Some species evolved to become nectarivory, their long and arching bills curved in the perfect shape to reach into Hawaiian flowers. Others still adapted to eat seeds, fruits, and insects. 
“They’re probably one of the greatest examples we have of adaptive radiation,” says Lisa Crampton, the Project Leader for the Kauaʻi Forest Bird Recovery Project. “These are birds that are found in no other part of the world.”


Another aspect well recorded by researchers is the decline and near decamation of the entire species of honeycreepers. At one point, there were 51 Hawaiian honeycreepers species. Today, less than half exists. Earlier extinctions were caused by habitat loss via the clearing of Hawaiʻi’s native forests, the encroachment of non-native flora, and predation by introduced species like rats. However, it was not until the 1990s that “things really started to pick up,” Crampton says. 


Hurricane Iniki, a category four hurricane, hit Kauaʻi in 1992. Considered as the strongest hurricane to strike Hawaiʻi in modern history, its winds reached speeds of up to 145 miles per hour. “Not only did it do a number on individual birds, I mean we’re sure that some individual birds were just blown off the islands,” Crampton says, “but those massive winds really toppled the forests like matchsticks.”

It toppled a number of native trees utilized by the honeycreepers as their main habitat. Although the native forests were weakened, leaving a smaller habitat for the honeycreepers, the devastation left by Iniki seemed manageable, says Crampton. “They probably would have been ticking along OK, slowly but surely recovering from the hurricanes,” she says, “had we not had this additional massive whammy from avian diseases.”


In the last two decades, cases of avian malaria have soared due in large part to rising temperatures caused by climate change. Avian malaria and the mosquitos that transmit them have long been known as threats to Hawaiʻi’s native birds who have no evolved defense against the diseases. 


However, in the late 1960s when avian malaria was first being observed, the disease’s reach was limited to the islands’ lower elevations where the warm and humid temperatures near the coast allowed mosquitos to thrive. In 1967, according to biologist Richard Warner, the mosquito line was restricted to 2,000 feet. 


“Everyone thought that the [ʻAlakai] Plateau was safe because it was so cold up there,” says Crampton. Today, she says, it is only safe for part of the year. Recent reports show that mosquitos are being found in Kauaʻi’s ʻAlakai Plateau—thought of until recently as the honeycreepers’ last refuge—as early as April. Their numbers last almost the entire year, persisting up until December. 


This combination of an increasingly warming Earth and the expansion of disease-carrying mosquitos’ reach have compounded the effects of an already tenuous situation, says Crampton. The akikiki and the akekeʻe in particular have less than a thousand individuals left. Their steep population decline have caused conservationists to set “the last ditch effort,” as Crampton describes it, of capturing their eggs and hatching them in captivity. 

“Already in Kauaʻi many of the forest birds are at such low numbers,” says Kristina Paxton, a post-doctoral researcher at the University of Hawaiʻi Hilo. “We were really interested in how their vocalizations have changed and how that could be affecting their populations.”
Paxton picked up on Kuhn’s observations, intrigued by the possibility that the honeycreeper species could be trading songs.


Along with evolving traits unique to their ecological niche, each species also evolved their own repertoire of songs. Honeycreepers are songbirds at their core. Their trills and note sequences distinctive to their species. “The vocalizations of the birds are how they identify a home range, claim it as their own. It’s how they attract mates,” Kuhn says. “The songs are how they organize their lives.”


Paxton’s team compared archival recordings of the honeycreepers’ songs from the 1960s and 1970s with ones from today. By analyzing aspects like frequency, the number of notes in a vocalization, and the repetition of trills, they can see how the songs have evolved over time.

I.
 
II.
 
III.
 

The research showed that compared to those from half a century ago, the songs of honeycreepers today are less complex. The steep declines in population in the last two decades have caused a loss in song diversity. Fledglings now have fewer adults from which to learn wider song repertoires, leading to songs that are less rich and intricate than their ancestors. 


“From one standpoint, it’s showing you how dysfunctional the birds are becoming,” says Crampton. Loss of song diversity, she says, points to the larger issue of the viability of the species. There is potentional, according to Paxton, that this shifting songs could affect the species’ ability to mate.


“We know that the birds pick their mates based on their songs,” she says, and so, if the trend continues, breeding failure would push the birds over the brink into extinction.


“This paper,” Kuhn says, “its not a happy project. It’s not something I’m celebrating. I’m very sad that it has come to this.”

IV.
 

There is hope though, stresses Crampton. At the capture and breed programs in the Keauhou Bird Conservation Center and the San Diego Zoo, conservationists are playing recordings made by Kuhn from honeycreepers in the wild.


“There’s a useful side to what David is doing,” Crampton says. “It’s not just an archival or a documentary project, there’s a very applied side to it.”

Conservationists hope that in playing sound recordings of their counterparts in the wild, birds in captivity will pick up on the nuances of their songs. The recordings have the potential of helping the birds learn a complex repertoire, like the ones of their ancestors.

 

Although research on this is still preliminary, it is in the hopes that "when they are released into the wild," says Crampton. "They can be the founders for their species."


“It makes me happy,” Kuhn says, “to think that the sounds I’ve left behind when I’m gone will be valuable.”
 

An akekeʻe in the wild, one of Kauaʻi's endemic honeycreepers. Today, its population numbers at less than a thousand. Photo courtesy of Kauaʻi Forest Bird Recovery Project.

David Kuhn has been guiding almost all of his life. He first noticed that the honeycreepers' songs

were disappearing ten years ago.

Data showing the loss of song diversity in three Kauaʻi honeycreepers over time. The discovery points to the larger problem of honeycreepers' steeply declining populations.

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