Nature fades to deafening silence

Nature’s soundscapes hoard far more information than we get from merely watching. Many animals hide from us - from birds to mammals, insects to amphibians. But they emit vocalizations that betray their presence. Carefully listening to them allows us to discover the true essence of nature. What are they telling us? Well, it’s not good news that’s for sure, as this article explains.

The sounds of nature form a constant and vital symphony. An expert in the field, Carlos de Hita, says that “sound is the story nature tells about itself”. When animals sing, croak, stridulate, growl or bellow, they are telling us a story which we can interpret or, simply, enjoy. But the increasing absence of these sounds in many natural environments reflects a worrying environmental degradation which is endangering biodiversity and ecosystem equilibrium.

 

Silence doesn’t exist in musical soundscapes

Carlos de Hita is a specialist in “traveling to listen”, which he writes about in his book “Sonidos del mundo” (“Sounds of the world”), Anaya Touring 2022. This explorer of nature’s soundscapes, who has spent four decades professionally recording sounds from nature across the world, is in no doubt. “Today there are fewer voices coming from nature,” he warns. Yet the immense majority of the population, ever more urban and disconnected from natural environments, are not aware of the problem. “We are becoming deaf to nature, to the point where its sounds are becoming exotic to us instead of normal.”

              “Our human world is every day noisier, but, paradoxically, nature is becoming ever more silent.”

Weary of noise pollution in the city, many people believe it is normal that nature should be silent. Indeed, they head to the countryside in search of silence. But, as Carlos de Hita never tires of telling us: “Silence does not exist in nature, at least in acoustic terms. What we call the silence of the countryside is really tranquility, which does not exclude sound, but does disturbance. This is because, acoustically, silence only exists in the vacuum of outer space.” Our human world is every day noisier, but, paradoxically, nature is becoming ever more silent.

 

Acoustic fossils

Loss of the intensity and diversity of sounds in ecosystems reflects a worrying decline in healthy biodiversity. Experts now refer to what is known as “acoustic fossils”, sounds in danger of extinction. Not so much because some singing species are disappearing, but above all we are losing the great orchestras, those spectacular soundtracks which have been welcoming in the spring for 100 million years and sound increasingly thinner, since they can count upon fewer vocalists and those who are left sing with less gusto and for shorter intervals.

“The dawn chorus now has less substance, is shorter and no longer the cacophony it used to be,” adds British ornithologist Dave Langlois, author of the fabulous book “Los cantos de las aves. El orfeón olvidado’ (The songs of the birds, the forgotten orpheón), Tundra, 2022. Calling on 75 years of experience actively listening to birds, he laments that “now the dawn chorus doesn’t last even half an hour; it’s at the most 10 minutes and at half gas”.

Several scientific works document this impoverishing of nature’s soundscapes, which are changing and drowning in silence. A 2021 study published in Nature magazine on 200,000 natural areas in North America and Europe found a generalized loss of acoustic diversity and intensity in the natural soundscapes of both continents in the last 25 years, driven by reductions in the diversity and abundance of species.

The oceans are also quietening due to pollution, noise from vessels, and climate change. Since 1950, the world has lost over half of its coral reefs. Diving in them is to swim in sepulchral silence.

 

Silenced ecosystems

A phenomenon known as “ecological silence” is a clear symptom of the present environmental state of affairs. The disappearance or diminishing of animal species due to deforestation, pollution and urban expansion causes the loss of its most distinct sounds. Indiscriminate felling of forests, for example, doesn’t just eliminate the habitat of innumerable species, but drastically reduces the songs of birds and insects that form the soundscape. The absence of natural sounds also has direct implications for ecological balance. Sounds fulfil essential ecosystem functions: they facilitate communication between individuals of the same species, warn of the presence of predators, and permit the synchronization of their reproductive activities. Without these sonorous elements, the vital cycles of many animals face alteration.

Variations in temperatures and climate patterns also directly affect natural habitats, forcing migration and local extinctions. The disappearance of animal and plant species contributes to the deterioration of the natural soundscape. Also, noise pollution generated by human activities in natural areas means that the sounds of the fauna are difficultly perceived, imposing yet another barrier to animal communication.

 

Bioacoustics is the study of the problem of natural soundscapes

If sound is so important, it is thus logical that we need to listen out for it carefully on all sides. This is the field of bioacoustics, a discipline analyzing the sounds produced by living beings and their relationship to the environment, a specialty which has become a fundamental tool for the study of biodiversity.

By recording and analyzing natural soundscapes, scientists can identify patterns of presence, distribution and behavior of species. Bioacoustics allows them to detect species which are difficult to observe directly, monitor large ecosystems and assess the impact of human activities on fauna. Its application not only helps to document existing biodiversity, but also conduct more effective conservation strategies.

“By recording and analyzing natural soundscapes, scientists can identify patterns of presence, distribution and behavior of species”

Thanks to the latest technological advances, which allow the use of ever more sophisticated sensors to record for months on end, and the use of artificial intelligence permitting automatic identification of sounds, researchers can obtain a detailed view of the abundance, and taxonomic and functional diversity, of species more or less in real time.

Hundreds of thousands of microphones have now been installed across the world, programmed to record automatically thousands of hours of natural soundscapes. Complex algorithms are used, similar to voice recognition technology in our mobile phones, to identify which species each song belongs to, and even the environmental conditions they are living in. This way, information is obtained which can be measured, standardized and analyzed, allowing their evolution to be established and which can be shared to cross-check between regions and against old recordings. But the results, it should be pointed out, are far from rosy. Researchers like Professor Steve Simpson of Bristol University detected places where indeed there is a “sepulchral silence”.

Living creatures are incredibly sensitive to climatic conditions. We need very specific levels of rainfall, humidity and temperature to be able to reproduce and survive. As these conditions become less favorable for some species, they sing less because their numbers are falling and they do it at different times, or they simply stop singing and disappear. We are losing singers and those who remain are losing energy. This represents a clear impoverishing of nature’s soundtrack.

 

The silent spring

In 1962, the US biologist Rachel Carson already warned in her famous book “Silent Spring” that, if humanity did not stop destroying nature, especially through the use of pesticides such as DDT, the number of birds and other wild creatures would continue to diminish and silence would begin to reign over the natural world. Her fears turned into an unerring prophecy.

“Preservation of natural sounds is not only an esthetic or cultural question, but a vital indicator of the state of our ecosystems”

 

A great silence is overcoming the natural world, while the sound of mankind is becoming deafening, says Bernie Krause, musician, scientist and naturalist, in his book “The great animal orchestra” (Factoría K, 2021). In 1993, he pointed out that the more diverse the ecosystem, the more sound variations it has and the healthier the environment. On the other hand, if the range of noise is reduced, there is evidence that biodiversity is being negatively affected.

 

Preserving natural soundscapes preserves the environment

Faced with the evidence of a growing loss of natural sound, it is crucial that we implement effective measures to conserve and restore ecosystems and help recover the sounds de Hita describes. Protection of nature reserves, reforestation and noise pollution regulations are essential actions for recovering the sounds nature has lost. Also, initiatives such as recording and monitoring of natural soundscapes can provide valuable data on the state of biodiversity and its evolution, and guide effective conservation strategies.

Preservation of natural sounds is not only an esthetic or cultural question, but a vital indicator of the state of our ecosystems. Listening to nature attentively helps life to flourish, ecosystems to keep their balance, so protecting biodiversity.

The fight against environmental degradation should therefore include a commitment to return to the world its natural voice, guaranteeing a future in which silence is not tantamount to loss, but space in which to contemplate the living harmony of nature.