Sounds Wild and Broken, page 28
In the indigenous oak forests of the region, I heard, on average, six bird species at each survey point. As I moved from point to point, the species changed, revealing variations in habitat. In all, I encountered forty-three species in these forests. Some were very common. I heard the singsong warbling of the red-eyed vireo at nearly every point. Others, the whiny scolding of the blue-gray gnatcatcher, for example, I found only occasionally. But overall, the bird community had an even mix of species, a community with many voices, not dominated by a small number of species. In older pine plantations, this diverse weave of sound was thinned to frayed muslin. Each survey point averaged four species. Across all survey points, I found twenty species. The birds tended to be the same from one place to another, dominated by red-eyed vireos and pine warblers. Younger plantations, those whose trees were just a few years old and grew ankle to shoulder high, were similarly simplified, but inhabited by birds that prefer thickets and forest edges, like indigo buntings and field sparrows.
My surveys showed not only that plantations were depauperate places for bird diversity, but also that the rest of the rural landscape was, contrary to the claims of the plantation apologists, home to rich communities of birds. Both rural residential areas and forests that had been logged but then left to regenerate without herbicides or bulldozing had bird diversity as high as or higher than that of mature oak forests. These lands retain large patches of forest, and thus many bird species, but also include brushy areas and fields that attract sparrows, buntings, wrens, and others. From the front porch of houses in these wooded areas, you can hear ten or more species singing at any one time. In all, rural settlements were home to more than sixty species in my surveys.
My surveys were possible only because of birdsong. At least 90 percent of the birds I detected I heard but did not see. Of course, such a survey misses all the silent birds—those sitting on nests, occupied with feeding during my visit, or whose singing peaked earlier in the spring—but nonetheless, aural surveys give an index by which to compare habitats. In all, I noted 4,700 individual birds across the five hundred survey points. Fed into graphs and statistical analyses, my experience of the presence of these animals was given legitimacy by the language of science and thus communicative power within human institutions. In the end, my surveys, and the extensive work of habitat mapping and analysis by a dozen colleagues, persuaded a national conservation group to successfully pressure timber corporations to stop converting native forests to plantations and to work with the state to set up conservation lands. A victory, of sorts, although by then most of the corporate-owned land had already been converted and would soon be spun off to private investment firms as part of a continent-wide divestment of land. To this day, local economies receive little economic benefit from these forests and plantations.
Maps demonstrated the extent of forest changes—from 1981 to 2000, 14 percent of the oak forest was converted, mostly to pine plantations—and analyses of bird surveys showed how these changes affected wildlife. Such graphs and statistics help us to understand and communicate. But they also serve as a substitute for lived experience by decision makers. In the Manhattan lawyers’ offices where the fate of the forests was decided in a meeting of besuited corporate CEOs, forest managers, scientists, and conservation advocates, few people had spent more than a few hours on the land they controlled. There were no representatives of local communities present. In the absence of the scent of trees, the varied songs of birds, the sight of running water, and the feel of soil and tree roots in fingers, a handful of graphs had to suffice.
The sustained direct sensory experience that is the root of human aesthetics, understanding, and ethics has almost no place in our corporate structures. For large businesses and nonprofits, and for many parts of government, listening is present only in highly mediated forms.
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The pine plantations I surveyed were not silent, but their soundscapes are impoverished compared with the forests they replaced. This method of growing and harvesting wood pulp directly suppresses sonic diversity. And so it is across much of Earth. Worldwide, human needs and desires are curtailing and extinguishing the voices of other species. We live in a time of rapid diminishment of sonic diversity, both in the direct extinction of other species and through the shrinkage of habitat.
Humans, especially those of us in industrialized societies, now use 25 percent of all the energy captured and made available by plants across the world, a percentage that doubled during the twentieth century and is still increasing. One species among millions takes one-quarter of the available energy and matter at the base of the food chain. In regions where agriculture dominates, our take is much higher.
Areas free from the yoke of human management are shrinking. Earth lost nearly twelve million hectares of tree cover in 2019, nearly four million of which was primary forest in the tropics, a continuation of a decades-long pattern. The loss is not evenly spread, however, with forest losses concentrated in the tropics and gains in many temperate regions such as abandoned agricultural land in Eastern Europe. Yet even in places such as North America and Europe, where tree cover is in some regions expanding, old-growth forests are still being cut, as in the Pacific Northwest and Poland’s Białowieża Forest. Other terrestrial habitats are also in decline worldwide. The area of cultivated pasture has increased, but natural grasslands have declined by up to 80 percent. The area of coastal and inland natural wetlands has halved globally. We are narrowing the foundation of the rest of the biosphere. No wonder biological diversity in all its forms—genes, species, sounds, cultures, communities—is in retreat.
Sonic decline is a symptom of the loss of biological diversity. But sonic diminishment is not only an indicator of loss. Sound connects animals in the present moment, sustaining their vitality by uniting them into fruitful communicative webs. The silencing of ecosystems isolates individuals, fragments communities, and weakens the ecological resilience and evolutionary creativity of life.
Sound might also guide us to be better members of life’s community. Listening connects us directly to Earth’s living communities, grounding ethics and action. Lately our ears have received technological help from computerized recording devices. Unlike my bird surveys in Tennessee, these electronic ears hear the entire soundscape and can discern patterns across vast troves of sonic data. This promises deeper awareness of the voices of thousands of animal species, perhaps guiding more effective conservation action.
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A diesel truck idles in the street outside, a thin plume of dark smoke wafting over the curb and across small suburban lawns. Its rumble penetrates the house and settles in my chest. The air is dry, prickly with smoke from Rocky Mountain wildfires and ozone from traffic and oil drilling. Underfoot, tufts of plastic fiber sprout wall to wall, years of wear evident in their uneven thatch. More than three months into the COVID-19 lockdown, the honey locust tree poking between concrete driveway and lawn has been my spring and summer forest. The tree is a transplant from forests to the east, planted among Austrian pines, Japanese maples, and native cottonwoods in what was shortgrass prairie, now part of the vast spill of suburbia across the Colorado Front Range. Often there are no bird or insect sounds here, or their voices are few: house finches nesting in gutters and field crickets chirping from the grass around irrigation nozzles. Instead, the soundscape largely comprises a seethe of traffic, droning heating and air-conditioning systems, hiss and spatter from lawn sprinkler nozzles, mowers and leaf blowers, and a smeared canopy of airplane noise from flights headed from Denver to the West Coast. On the edges of town, in the protected areas set aside by town planners, the traffic sounds blend with animal voices indigenous to the region: the whistled songs of meadowlarks, yips of prairie dogs, and the gruff cries of patrolling ravens.
Headphones on. Borneo: a forest in East Kalimantan Province, Indonesia, just two hundred kilometers north of the equator. I pull up a two-day continuous recording from a site in a lowland rain forest that, as far as anyone knows, has never been logged. The microphone sat in a weatherproof box hung from a tree. Researchers set up and retrieved the device but otherwise left it unattended. The eavesdropper turned the moment-by-moment life of the forest into accretions of data in a memory chip. Later this sediment of zeros and ones was copied to a laptop computer in the field, then to a server in a lab in Queensland. I press play, and the sounds of the tropical forest reawaken in the miniature magnetic coils and paper cones in my headphones in Colorado. The sound is an obedient phantom, a presence removed by human technologies from its living sylvan bodies, resurrecting on our command.
The sound is disembodied but still powerful. I cue the digital sound file to midnight in the forest and drop into shimmering insect sound. At least fifteen species are singing, and their voices cover almost all the audible range, except for the very lowest frequencies. The singers differ in the texture of their sounds, some silky, others raspy or bristly, but they are so tightly packed that I feel as if I’m suspended in a dense, lustrous cloud. The snap of falling water on waxy leaves adds an irregular beat. This is not rain, but the fat drops that fall from the tree canopy in a downpour’s aftermath. A distant croak pops into the lower registers, perhaps a tree frog in the canopy. I drift in the sound, letting the insects carry me through the Bornean night. A few voices hold steady, a bright drone. Some pulse second by second or rasp in short bursts. Others swell then recede like ocean swell, cresting every fifteen seconds, then easing back.
I wake at 1:30 a.m., Borneo time, ninety minutes after starting the playback. The forest’s sounds lulled me to sleep. My ears, perhaps starved by suburbia for the diverse voices of forest life, reached into me and dialed back my consciousness. My sleep had a familiar texture, not groggy or fogged, but clear, like immersion in the refractions of water. The only other time I sleep this way is under trees when I’m taking a break from hiking or when I’m in a tent in the forest. For fourteen million years our great ape ancestors slept in tree nests. This dip into sylvan sleep might be a hazy remembrance, wakened by my ears, of a long ancestry.
Refreshed, I return to the soundscape of the Bornean forest. As the night progresses, insects continue to dominate, peppered with some thumps and twangs that I take to be frogs. Birds and primates are silent. At 3:00 a.m., the fat, even weave of trills and burrs has spun into two thick cords of trilling. Many of midnight’s insects have dropped out and now half a dozen species dominate the air. By 4:45 a.m., new insect sounds, zips and chirps, take over from the steady trillers. One katydid’s rasps are so soft and low that they are almost like bleats. Then, six minutes later, the first sound from a bird, a rapidly repeated tut, like water dripping fast from a faucet, the predawn call of the Bornean barbet, a jay-sized bird that lives in the forest canopy, its green plumage blending with the foliage as it hunts small animals and gobbles fruit. Many trees in these forests rely on the barbet and its kin to disperse their seeds. Distant whistled bird cries follow a minute later. Then, close to the microphone, rough, vigorous croaks, coming first alone, then in twos and threes, crac crac-CRAca cra-CRA. Rhinoceros hornbills—giant fruit-eating birds of the primary forest—are waking and sharing their morning greetings. Bird whistles and fluty notes from half a dozen species build over the next ten minutes. As the sun rises and the day unfolds, cicadas emerge, buzzing like those I am familiar with in temperate forests. A few screech like the whine of a drill or scrape like a knife on a sharpening stone. At dusk, dawn’s crescendo of bird sound returns, then gives way to crickets and katydids.
I delight in these sounds, imagining the rich forest around me. But I also feel an uneasy sense of dislocation, especially if I listen for more than a few minutes at a time. My ears are fully immersed in one of the most diverse places known on the planet, but the rest of my body, including all my other senses, is in a rental house in North American suburbia. The rain forest is spiced with thousands of leafy, fungal, and microbial smells. Every tree has its bouquet, and the soil rewards nasal explorations with striking aromatic variegations. I breathe only truck fumes and the exhalations of a house interior, backed by haze from tens of thousands of fracking wells east and north of town, and a dense network of busy roads. Ants, beetles, and leeches swarm the forest floor, necessitating regular plucking from human ankles and legs. My feet now feel only the scratch of carpet fibers on bare soles. The humidity and warmth of the rain forest air blur the boundary between forest and human. There, human sweat and the dripping moisture of leaves merge, as if tree sap and human blood were one. Suburban heat, though, rises lifelessly from asphalt and is walled out of house interiors. My eyes see three plant species from my desk and, if I’m lucky, a couple of birds, not the hundreds of the rain forest. Even my gut is in a different sensory world than the sounds in my ears, well fed with nutritious food, but dissociated from the flavors and textures of food traditions around and in the forest.
Is this what human musicians felt when wax cylinders first played their music back to them? The music is there, faithfully recorded, but is removed from the contexts of place, sensory presence, and living connection. Is this what the first readers of the written word felt when language that formerly lived only in the breath was encoded on a page? I have spent my life immersed in recorded music and the written word. Through the motion sickness that I feel in this extended listening to the rain forest, a queasiness I have never felt in a living forest, am I tasting what we lost when we forsook aural culture for written words and recorded sound? For our ancestors, listening and speaking were entirely embedded within all the senses and in a singular place and time. Now music and words arrive through ears or eyes only—ears in headphones, eyes on books—and are deracinated from their place of origin. I love my records and, yes, books, but wonder how their abstractions (from the Latin abstrahere, “to drag away or divert”) have shaped me.
I dive back in. Despite the undertow of unease, I revel in these marvelous records of one of Earth’s most diverse and striking soundscapes. I click and listen again to the hornbills’ waking and the cicadas’ saws. Then I upload other sites from the same forests, some unlogged and others growing back after a selective commercial cut of their trees. These recordings were made as part of a research study led by Zuzana Burivalova, a professor at the University of Wisconsin, with colleagues from conservation groups and universities in Indonesia and Australia. Through multiple sound recordings across seventy-five different sites, they hoped to assess how the animal diversity of the forest was faring and make recommendations for future conservation in the region.
These recordings are staggeringly varied. At each site, hundreds of voices come and go over twenty-four hours. As I skip around in the digital sound archive, I land each time in what, to my ears, is a different sonic world. These sonic patterns are nothing like those of the cities and forests of the temperate world. Midnight in New York City is a little noisier than two in the morning, but the types of sounds are the same: sirens, airplanes, cars, and chatter on the street. Dawn in an old-growth forest in Tennessee has many more voices than noon but is largely composed of the same singers. The timbres and rhythms of sounds cycle over days and nights in these places, but not with the same granularity as in the Bornean forest. Time is denser and more finely textured in tropical forests than elsewhere. The same is true of space. As I click from one site to another, I hear contrasts matched only by the most extreme differences in the temperate world, as if I were walking from a deeply shaded forest into a swamp or open meadow, or from a busy street into an urban park. Every site in these recordings has a vigorous character of its own, defined by many layers of insect sound and hundreds of different bird, frog, and mammal calls.
As I think about the researchers, I feel a pulse of anxiety at the thought of trying to quantify the differences among these sites. These recordings comprise more than three thousand hours of digital sound files. It would take more than a year of full-time work just to listen to every recording.
Enter big data for sound. Thanks to software developed by a team at the Queensland University of Technology and Burivalova’s coding and statistical analyses, we can listen for acoustic patterns in lengthy sound recordings. The software slices every recording into one-minute segments, then dices each one-minute sliver into more than two hundred frequency segments. In this way, the continuous stream of sound is cut into countable pieces. The software then looks for patterns across the whole soundscape. How, for example, do the loudness and the frequency of sound differ among sites? Is the sound saturated at some sites, with every frequency and minute filled, but more threadbare in others? How do these patterns change over the day and night?
As we’d expect from experience in the forest, the computer found a peak in the saturation of the soundscape at dawn and dusk. These are the clamorous choruses of birds, frogs, primates, and insects that mark the rising and the setting of the sun in tropical forests worldwide. Both logged and unlogged forests showed these peaks. Night was less saturated with sound in the unlogged than the logged areas, likely because some night-singing animals like katydids and some frogs are especially abundant in the open areas left by selective tree felling. In the day, unlogged forest was more saturated, a reflection of the more diverse animal communities in these forests. These are the kinds of patterns that human observers readily notice and have, over many decades, quantified with clipboard-in-hand field surveys. Selectively logged forests are home to many species, but their living communities are usually less diverse than in unlogged forests.
The analysis also found patterns that time-limited traditional surveys would likely miss. In particular, the logged forest was more acoustically homogenous than unlogged areas. As my naive ears listen to a fraction of the sound recordings, all the sites sound fabulously different. But the software was able to hear beyond such human limitations and precisely measure how similar the sites are to one another.
