David George Haskell is an American biologist and author who is currently a professor of biology at The University of South Tennessee. He has published two books to date: The Forest Unseen (2012) and The Songs of Trees (2017). Both were nominated for a number of major literary awards (including the Pulitzer Prize), the latter receiving the John Burroughs Medal. The final chapter of the same book was even adapted into an award-winning short film for virtual reality. The Atomic Tree (2019). Book The Forest Unseen, in which the author follows a small section of forest over the course of a year, has been translated into ten languages, including Czech (under the title Secret Forest published by Universum Publishing House). Haskell regularly contributes to The New York Times and Emergence magazine. Haskell's texts are an excellent example of the modern form of natural history literature; the contemplative and lyrical aspect in them gently meets the scientific foundation; the emphasis on detailed (almost poetic) evocation of sensory experiences, especially smell and hearing, is also undeniable. (The author will publish a book later this year Thirteen Ways to Smell a Tree, in which he talks about trees from the perspective of discovering their aromas and scents. Next year, he is preparing to publish a book about the sound diversity of living nature and the art of listening, entitled Sounds Wild and Broken.) Haskell's texts lead their readers to a direct experience with the countless forms of non-human life, to a direct sensory experience with the surrounding (intimately close) world. This is also the central theme of the following text from Emergence, in which the author discusses birdsong and the meanings that, if we are attentive enough, we can read in it. Selected and translated by Luděk Čertík.
For millennia, the voices of birds have encouraged us to overcome our differences. In the Quran, Solomon is rewarded and blessed with the language of birds. Job calls us to listen to the wisdom of winged celestial beings. News from the human world was brought to the divine ear by the talkative ravens of Odin and the blue-colored birds of the Taoist Queen of the West. In the voices of birds, oracles, omens, prophecies speak to us. They beckon us across borders to other times and places.
Listen: an invitation. But what exactly the language of our winged relatives communicates is not easy to determine. The bodies that birds inhabit are fundamentally different from ours. Our lack of attention makes bird language even more distant from us. We separate ourselves from birds by brick walls that keep us captive in inner spaces, inside worlds created by human hands. And by assumptions, strictly guarded in the vaults of the mind. It is we who have made ourselves such a lonely and silent place.
Let's let the sound in.
From their open beaks, song pours forth from the birds’ chests. Here, at the junction of the bronchi, just above the heart, lies a sound-producing organ of unique and wondrous appearance. The syrinx, as it is called, is only as big as a lentil or bean. Woven into this tight space are a multitude of muscles and cartilage rings connected by a thin sclera to the delicate tissue of the lips. The muscles, capable of two hundred contractions per second, are among the fastest ever. As the exhaled air passes through, the lips tighten and the quivering sclera transmits the song to the air. In milliseconds, the sound is modulated by extremely precise twitches in the muscle and cartilage. Birds are nimble jewelers of the air, creating dozens of decorative jewels at any given moment. The birds’ modulations of pitch, range, and timbre speak of the vitality of their blood, muscles, and nerves.
But we don't hear the same things they do. For at least 300 million years, mammals and birds have followed separate evolutionary paths. Our common ancestors, amphibian-like creatures of the wetland forests of the Paleozoic, had hearing adapted to aquatic environments. Their descendants, birds and mammals, each independently evolved hearing organs adapted to air. Bird and mammal hearing are thus built on two distinct architectures: more linear and direct in birds, segmented and coiled in mammals.
Bird and mammal brains have also taken different evolutionary paths. Neurons are literally crammed into bird skulls, giving tiny bird brains a comparable number of nerve cells to much larger primates. The folds and layers of the forebrain have a different geometry, hierarchically layered in mammals and grouped into nodes in birds. Bird brains and bodies are also several degrees warmer than mammals, which stimulates chemical reactions and therefore speeds up nerve responses.
All of this translates into a different perception of sound. Birds are sensitive to rapid acoustic changes, and their hearing is focused primarily on mid-range frequencies. They perceive not so much relative pitch as the overall shape of the sound, the subtle nuances between layers of sound frequencies. Or so it seems from the small number of studies that have sought to understand the act of hearing from a bird's perspective.
We are faced with two parallel worlds of experience. The same sound vibrations are received and evaluated in fundamentally different ways by birds and mammals.
As we listen and seek to connect, we should remember and honor this difference. But let us not allow our differences to stifle our curiosity, our imagination, and our sense of kinship. There is a bridge. That bridge is the gift of our attention. Sometimes science draws on this gift, but more often it opens the doors to bird languages in our everyday lives.
What do we hear in the bird calls of our homes? Each species has its own sound signature, and individuals within a species have their own unique voices. In this diversity of acoustic expression, different meanings are represented.
First, there are the peculiarities of the species, the cadence and tempo that are peculiar to each one. Garden wren. Bald eagle. Song sparrow. Raven. By noticing and trying to name them, we take the first steps towards establishing friendship and understanding that bridges the gap between species. Sound is a particularly powerful bond because it travels to us through and around obstacles. It thus speaks to us and awakens us from our inertness. We walk through the city and notice our avian relatives. Affinity and community are no longer mere ideas, but lived, sensory-anchored relationships.
One layer of bird language is therefore the numerous meanings and messages heard in the community of bird calls. The rhythms of the year are written into the air by the constantly changing sounds. The arrivals and departures during migration: of tropical songbirds, snow geese from the tundra, cranes from inland wetlands. Baby birds call out to their parents from early summer. Chirping swallows warn of the appearance of hatching river mayflies. Sparrows call out inquisitively from the winter undergrowth. Over the course of the year, each species has its own sound-forming tempo, controlled by local weather and tuned to the peculiarities of insects and edible, fruit-bearing plants. Through these sounds, we discover that there are not just four seasons, but dozens and hundreds. The voices of birds reveal the polyrhythms of the living Earth.
Bird language also reveals the physical diversity of the world. The cry of a gull cuts through the roaring winds of an ocean coast. In a mossy forest, a sandhill crane makes a deep-sounding territorial call that cuts through the dense vegetation as if nothing were in its way. High in the mountains, American millermen converse with each other in tones that cut through the howling wind in the spruce crowns like the edge of a knife. Eagle owls hurl their spear-like songs across the thick grasses of the open prairies. Every sound has a home.
The rumble of fossil-fueled industrialized humanity is creeping into these homes. We are spreading low-frequency rumble and rumble throughout the world. The birds closest to the swamp of engine noise are forced to sing louder and in higher registers, otherwise their voices will not stand out in the noise and will disappear. Others, especially starlings and house sparrows, are content in this new world, finding in it a wealth of opportunities for acoustic and ecological improvisation and discovery.
By paying attention to the sounds of bird species, our senses learn the language of belonging. Over time, this embodied knowledge of place begins to tell us what has been touched by change, what has been added and what has been lost.
In the years to come, our descendants, our students, and our friends will need our stories. By listening to the birds, we can gain something valuable for future storytelling, stories whose meaning is not yet apparent: that ravens fell silent in the heat of high summer, that sandhill cranes showed up in March but stayed only briefly, that truncheons and tyrants wove their summer songs into the crowns of cottonwoods, and woodpeckers left the suburban firs in December. These will be stories of continuity, of extinction, of flourishing, of altered tempo and texture. Future generations will count on us to be able to articulate these living memories. Listening in the present is a beginning.
But there is another richness hidden in the stories told by birds. Each individual bird has its own sonic signature. Listen and learn the voices of your local birds. Some species reward our attention by revealing their sonic identity almost immediately. Across much of North America, the songbird is one such teacher. Each singing male has his own repertoire and style. Listen for a few minutes, and the individuality of their voices will fly into your consciousness.
It is more difficult for us to distinguish the individuality of the voices of individual species. The sneeze songs of tyrants seem to the untrained ear to be exactly the same, although the birds recognize each other by their voices. Ravens, on the other hand, express themselves with such complexity that we can only wring our hands helplessly. We are tuned to the melodies of human music, and the multiple shades of the raven's cawing, clucking, and whistling put us in a bind. Unlike the bunting, which sings day after day in our immediate neighborhood, providing us with continuous lessons in its squeaky melodies, ravens are scattered over vast territories and allow us only very limited access to the inner dynamics of their speech.
With a little attention, and perhaps even the help of a recording device, we can recognize the distinctiveness of the birds around our homes. But understanding the meanings embedded in those sounds is not so easy. In the human domain, I can learn to distinguish the individual voices of people speaking a foreign language, but that does not allow me to understand what they are talking about or what the meaning of their words is. How much more difficult is such a task with creatures that are hundreds of millions of years away from us in evolution.
But attentive bird listeners hear some of these meanings. The individuality in bird calls is not free or random; it reveals the personality of each individual bird. In a community of tits, some birds have open and inquisitive personalities, while others are more cautious and anxious. The cawing of kingfishers and the evening song of the wood thrush take on entirely new nuances when birds are mating during courtship. On the nest, we hear information flowing in a flurry of sounds between paired birds. Two flightless tyrants do not ask for food in the same way. When young buntings chatter and practice their songs, they survey acoustic spaces in a way that is close to what happens in human speech: by improvisation, repetition, and training by listening to their elders. In the treetops at dusk, ravens chirp quietly to themselves as they preen their feathers. The call of a raven sounds sarcastic and ironic when the bird imitates the call of a sandhill crane for its companions. Laughing parrots cause birds in their vicinity to behave mischievously. When thrushes flock to the lawn, a crested jay imitates the call of a banded buzzard: it repeats the same deception with relish when people pass under a tree. This is not the sound of mindless mechanical clatter. Nor are these harsh, socially one-sided expressions of satiety or sexual satisfaction. These sounds are complex, layered, revealing sensitivity to external stimuli, creative, and imbued with humor.
Laboratory studies have revealed that bird speech is imbued with understanding and a high degree of imagery, organized by custom, driven by creativity, and shaped by culture and context. Bird sound production has internal grammatical rules. Bird brains are teachable and innovative. Birds hear and remember subtle nuances of sound, and connect abstract sound patterns with the material dimensions of their ecological and social worlds. They listen to the voices of other species and understand what is being communicated. Social interactions with relatives and neighbors shape their individual vocalizations and determine the organization of these utterances into a coherent form.
The aforementioned scientific studies, while valuable in deepening our understanding, have examined bird language in only a limited number of species, often with the aim of testing whether certain patterns of human grammar also appear in birds. So far, science alone is not enough for the task of listening to birds. A few experiments conducted by a handful of researchers will not open the human ear to the voices of our cousins. Language learning is accessible to everyone.
When we understand the meaning of the sound a bird makes, nerves in two different brains touch and begin to send signals. The vibrating air creates a connection between nerve cells, a connection as real and strong as the chemical bonds between nerves in a single brain. Bird calls are therefore sound neurotransmitters that transcend species boundaries.
Such a leap is creative. When avian and human minds connect, a new language is born. This expanded language connects many species into a single communicative whole, a network of listening and speaking. Learning a language is truly accessible to all without distinction. It unites us. And so we return to the invitation that the birds near our homes offer us. In their voices we hear the multiple rhythms of the seasons and the colorful physicality of the inhabited environments. We learn the unique stories of each bird. We become clear about the transformations our community is going through and what we should preserve from the present moment. We hear and shape the universal grammar of the Earth.
Let us accept the invitation of the birds and go outside to offer them the simple gift of our attention. Let us listen. Let us marvel. Let us become those who belong.
