Opinion: Listening to the biosphere is a key step to saving it | Abstract TS
IIn the spring of 2020, as COVID-19 lockdowns spread across the world, a University of Tennessee ecologist elizabeth derryberry headed for the Presidio district of San Francisco. In the eerie stillness she listened to the male white-crowned sparrows, whose beautiful songs begin with a long, clear whistle, followed by a rapid series of notes and rapid trills. How would the birds, she wondered, react to the unusually quiet streets? She carried with her a bioacoustic recorder, a digital listening device the size of a smartphone, aimed at collecting data to answer this question.
Birdsong is vital for the survival of some birds. By singing their songs in unique dialects, male songbirds can simultaneously provide information to potential breeding mates and keep rivals at bay, especially during mating season. Compared to their rural counterparts, urban sparrows tend to sing fewer, louder songs with reduced complexity and fewer trills; they also exhibit higher aggression and stress hormone levels, lay fewer eggs, and produce smaller nestlings. But in the newfound calm of a world plagued by a viral pandemic, the songs of urban sparrows has become more complex, found Derbyberry. The trills reappeared, rapid and complex. With no competing noise, their songs traveled twice as far, a boon to mating success. In contrast, rural birds in neighboring Marin County, where noise levels did not vary significantly during the shutdowns, showed no difference in their songs before and during the pandemic.
Listening to nature is an ancient art. But Derryberry is part of a new generation of scientists who have begun to listen to non-humans using digital bioacoustic recorders – inexpensive, portable and automated – to record sounds in remote locations, and also to capture sounds outside range of human hearing, from the infrasonic roar of whales and elephants to the ultrasounds of bats and dolphins. When combined with artificial intelligence algorithms capable of analyzing recordings for sound patterns, these devices function as powerful prosthetic organs, extending human perception beyond our limited sensory abilities. I take readers on a tour of this research and the auditory insights she uncovered in my latest book, The sounds of life.
As a species primarily dependent on sight, humans sometimes have difficulty imagining the power and richness of sound. But in the living world, sound is more universal than visual information. In the depths of the ocean, sound travels farther than light; aquatic species often hear better than they see. Even on earth, sound transmits in the middle of a dark night and can be heard from any angle or perceived as vibrations in the earth. Sound ecologist Bernie Krause describes this as the Earth’s glorious orchestra, a continuous sound of living and non-living entities, much of which cannot be heard by the human ear without aid.
By listening to nature’s chorus, scientists have discovered evidence of the universal importance of sound to living species through the tree of life. Many more non-human animal species use sound to communicate, in much more complex ways, than scientists previously thought. Bats begging and exchanging favors for foodand keep silent while they social distancing during illness“product[ing] fewer contact calls that attract affiliate teammates. The bees to whistle in anticipation of dangeruse unique buzz signals to describe the location of distant food sources with astonishing precision, and use specific signals that distinguish different threat levels posed by specific predators. Mother whales whisper to their babies hide their communications from predators. In some species of turtles, the embryos synchronize their collective moment of birth by make sounds through their shells, even before they hatched. Dolphins call each other by individual names (their “iconic whistles”) and will respond to recorded readings of these names. These findings challenge the outdated assumption that complex communication and language are unique to humans.
Perhaps most surprisingly; Species without ears, or any apparent means of hearing, also sense and respond to sound. When dispersed in the open sea, fish larvae and larval corals (the latter creatures only a few millimeters in size, with a rudimentary or non-existent central nervous system) feel the sounds of their native reefs to swim home. And in response to the buzzing of bees, flowers flood with sweet nectar, as in anticipation. The natural world is engaged in an ongoing conversation, of which humans, until recently, have been largely unaware.
But an emerging appreciation of the biological importance of sound has led to new strategies for environmental conservation. Scientists have successfully used bioacoustics to regenerate coral reefs. A citizen science movement has emerged: crowdsourcing data, making sound walks, and connecting to apps like Orcasound that allow anyone to listen to nature, anytime, anywhere.
Scientists are also using bioacoustics, combined with artificial intelligence, to try to develop translation devices. Researchers create dictionaries in Sperm whale and East African Elephantwhile others build robots that successfully communicate commands to bees. A zoological version of Google Translate maybe even on the way. This raises ethical questions: are we going to use our new ability to translate to further dominate or domesticate other species, or rather to protect them? Are we going to develop a new sensibility, a new way of relating to other species as non-human people, or parents? And why would they want to hear what we have to say?
In the midst of this debate, the urgency to tackle noise pollution has become increasingly evident. Noise from machinery and industry increases stress, disrupts embryonic development and can kill organisms instantly. The negative effects of noise have been documented in plants as well as animals. In humans too, chronic noise pollution is associated with an increase risk for the healthincluding cardiovascular morbidity and mortalitydevelopmental delays and dementia.
Silence the human din is one of the major challenges of our time. The silver lining: Reducing noise pollution has immediate, positive and significant results. Proposed regulations to limit noise pollution could have a huge benefit. We have much to gain – and learn – if we start listening to the natural world again.