For me, spring and Rachel Carson are inextricably linked. In her visionary, 1962 book, Silent Spring, Carson—a marine biologist and environmental trailblazer—wrote: “Over increasingly large areas of the United States, spring now comes unheralded by the return of birds, and the early mornings are strangely silent where once they were filled with the beauty of birdsong.”
Silent Spring was an indictment of the pesticide industry that arose in the late 1950s. The book presented a piercing look at the damage the chemicals that were in wide usage were causing to bees, birds, domestic pets, plants, wildlife—and humans. At the time it was published, she expected criticism, but she did not anticipate being personally vilified by the chemical industry and its allies in and out of government. She spent the last years of her life courageously defending the truth of her conclusions. She died in 1964.
I wish that Rachel Carson could know how right she was. Natural sounds, particularly birdsong, play a key role in building and maintaining our connection with nature. Now, 60 years after the release of her book, a major new study reveals that the sounds of spring are changing, with dawn choruses across North America and Europe becoming less varied and quieter.
Fortunately, however, new voices and new songs are arising, too. Perhaps they’re not lingering in our spring air as they once were, but they are surely making our waters and marine ecosystems seem more musical.
Although declining, the ballads of birds base us in nature
A paper published in the journal Nature Communications in November 2021 described a new technique that an international team of researchers developed to combine citizen science bird-monitoring data with recordings of individual species in the wild. Annual bird count statistics from North American Breeding Bird Survey and PanEuropean Common Bird Monitoring Scheme sites were matched with recordings of more than 1,000 species from Xeno-canto, an online database of bird calls and songs.
The audial characteristics of these soundscapes were then analyzed using four indices that measure the distribution of acoustic energy across frequencies and time. These indicators are driven by song complexity and variety across contributing species, but they also quantify the diversity and intensity of each soundscape as a whole. The researchers then used these results to help them reconstruct the soundscapes of more than 200,000 sites over the last 25 years.
Because of widespread declines in bird populations and shifts in species’ distributions in response to climate change, the scientists expected to find that the acoustic properties of natural soundscapes were changing. There were proven correct: they discovered that the soundtrack of spring—birdsong—is getting quieter and less diverse, and that one of the fundamental pathways through which humans engage with nature is in chronic decline.
Further, the researchers noted that sites that have experienced greater declines in either total abundance and/or species richness also showed more loss in acoustic diversity and intensity. For example, the loss of nightingales or skylarks—which sing rich and intricate songs—is likely to have a greater impact on the complexity of the soundscape than the loss of a raucous corvid or gull species. So, the initial community structure and how the call and song characteristics of species complement each other also play important roles in determining how soundscapes change.
The benefits of contact with nature are widespread, from improved physical health and psychological well-being to increased likelihood of participating in pro-environmental behavior. Given that people predominantly hear, rather than see, birds, reductions in the quality of natural soundscapes are likely to be the mechanism through which we will most keenly feel the impact of ongoing bird population declines. And, as we collectively become less aware of our natural surroundings, we also start to care or notice less about their deterioration.
While this is depressing news, studies like this heighten our awareness of these losses in a relatable way and demonstrate their potential impact on our health.
“Songs” from coral reefs mean successful restoration
Across the globe, coral reefs face multiple threats, including climate change and water pollution. To find a remedy, the Mars Assisted Reef Restoration System in Indonesia has been attempting to restore reefs by laying hexagonal, metal frames seeded with coral—called “Reef Stars”—over thousands of square miles. The Reef Stars stabilize loose rubble and hopefully kick-start rapid coral growth. But successfully growing coral is only part of the ecosystem. It had remained unclear whether these new corals would also be a boon for other reef creatures.
So, in 2018 and 2019, researchers took acoustic recordings of the reefs. The croaks, foghorns, growls, raspberries and whoops that they heard—many of which had never been recorded before—documented the return of a wide range of animals, and thus the reefs coming back to life.
In their study, published in the Journal of Applied Ecology in December 2021, the researchers stated that although there were significantly more fish sounds recorded on both healthy and restored reefs than on degraded reefs, the soundscapes of the restored reefs are not identical to those of existing healthy reefs. But the diversity of sounds is similar, suggesting a whole and functioning ecosystem with a better chance of becoming self-sustaining, since such sounds attract more animals that diversify and maintain reef populations.
This study proves that reef restoration can work, but it’s only part of a solution that must also include rapid action on climate change and other threats to reefs worldwide. If we fail to address these problems, state the scientists, conditions for reefs will continue to get more hostile, and eventually restoration will become impossible.
The notes of narwhals are the jingles of glacial fjords
Notoriously shy and skittish, narwhals spend most of their time deep in the Arctic Ocean. They tend to summer in glacial fjords around Greenland and Canada, but researchers often have trouble getting close enough to study them. Glacier fronts can be dangerous and hard to access, and the animals tend to swim off when approached by motorized boats.
But Inuit hunters familiar with the mysterious mammals know how to get near without disturbing them. In July 2019, scientists accompanied several Inuit whale-hunting expeditions departing from the village of Qaanaaq. They placed microphones underwater and recorded the baseline sounds of a fjord in Northwest Greenland to study the narwhals that summer there in more detail.
The researchers were able to get as close as 82 feet from the elusive cetaceans. They captured narwhal social calls, whistles and foraging sounds—the clicks used for echolocation, the biological sonar used by bats, dolphins and some whales to navigate and find food. The closer narwhals get to their food, the faster they click, pinpointing the location of their prey, until the noise becomes a buzz that sounds like a chain saw.
This study, published in the Journal of Geophysical Research: Oceans in April 2020, is one of the few to have documented narwhals feeding in the summertime. And, surprisingly, the scientists found narwhals come roughly within half a mile of a glacier’s calving front, even though these areas are some of the noisiest places in the ocean and calving icebergs can be hazardous.
As one researcher put it, “The narwhals’ world is the soundscape of this glacial fjord.”
Tunes of two roads
Sadly, today we are living through a global environmental crisis, and the diminishing connection between people and nature—exacerbated by the loss of birdsong—may be contributing to this. Rachel Carson also once wrote: “We stand now where two roads diverge. But unlike the roads in Robert Frost’s familiar poem, they are not equally fair. The road we have long been traveling is deceptively easy, a smooth superhighway on which we progress with great speed, but at its end lies disaster.”
I think it’s time to choose the other road. The one where coral reefs ring with songs and fjords funnel serenades.
Have a happy spring, and make it count.
Here’s to finding your true places and natural habitats,