Not So Silent Spring
A Sonic Revolution
Coming home late the other day, I was startled by sound as I crossed Interstate 5 on a pedestrian bridge north of our house. Of course there were the mellifluous rhythms of traffic but rising above that din was a sonic riot of Pacific tree frogs, also known as Pacific chorus frogs (Pseudacris regilla). They have the classic ribb-et, or krr-r-r-eek, call of a wild batrachian in love, or at least interested in mating. It’s so classic it’s often the sound one hears for any type of frog in a movie, regardless of the location (and you thought I dove down rabbit holes!).
These handsome frogs produce several types of calls. The mating call serves to attract females, who then base their mate selection on the call, but also to alert other males to the caller’s space. If that space is invaded, then the call changes to an encounter, or staccato, call. If the intruder fails to acknowledge his adversary’s warning, the two rivals bounce toward each other and whack each other’s vocal sac with their own. Continuing to staccato call, with legs flailing, the two then try to deflate the other’s sac. “The deflated frog would then swim away,” as researchers wrote.
Impressed and pleased as I was to hear the call of Pacific chorus frogs over the noise of Interstate 5, I know that they are affected by our aural emissions. Studies show a negative effect, with lowered reproductive success, increased physiological stress, and altered migration patterns. There doesn’t seem to be an end to how we can mess with our fellow inhabitants of planet Earth.
Spring has also brought another sound to my ear, the chattering, squawks, and squalls of the Steller’s Jay. These big blue birds, with their Elvish (the King not the mythological kind) hair style, are forever making a brouhaha. As Elliott Coues wrote in 1874, “they fret and scold about trifles, quarrel over anything, and keep everything in a ferment when they are about.” But as many have also written, Steller’s Jay are so splendidly interesting, that our forests—urban and wild—would lose their vivacity without the bird’s cacophony of observations and concerns, so I never mind their sounds. (Steller honors George Wilhelm Steller, who explored the northern Pacific with Vitus Bering (apparently he was the Strait guy of the pair).
With no disrespect to Rachel Carson, I didn’t actually write this essay to honor the sounds of spring that she helped perpetuate. What I really wanted to discuss is the book, Sounds Wild and Broken, by David George Haskell. He is revelatory in his explorations of what he calls “part of the world’s richness…the diversity of aural experience.”
What most intrigued me was thinking about the long history of sound. Whenever we hear wind or rain, rockfall or lighting, ocean waves or water rushing, we are hearing noises little changed over the past 4.6 billion years. A landslide on early Earth sounded like one that fell yesterday. In stark contrast, the frogs’ ribbits near I-5, the jay’s shaack, shaack, shaack in our backyard, or any other of the uncountable sounds produced by organic means, are recent developments. The earliest fossil evidence for a sound making structure is merely 270 million years old. Let me rephrase that, 94% of our planet’s history passed before sonic communication began.
The evidence of first sound comes from an enigmatic, cricket-like insect, Permostridulus brongniarti, that lived in the middle of the supercontinent of Pangaea. Described in 2003, the insect had a “bow of fused cross-veins…interpreted as a stridulatory apparatus.” By rubbing its wings together, the animal produced an audible rasp and biological singing was born.
Another 140 million years or so would pass before the true sonic revolution blossomed on land. The reason, flowering plants; their rapid diversification led to a corresponding evolution of insect species and their chorus of sounds. The other great songsters of the planet, birds, didn’t add their sonic repertoire until after 66 million years ago, following the great Cretaceous extinction, which also killed off the dinosaurs. (Despite what Hollywood would have us believe, dinosaurs were not aural communicators; they may have produced some windy utterances but not the emotive sounds popularized by the “Jurassic Park” movies.) Around 160 million years ago saw the evolution of the mammalian ear, which allowed our predecessors to hear high frequencies but what sounds they produced, we know not, and that diversity only exploded after the Cretaceous extinction. Organic ocean sound began around 200 million years followed by another sonic burst of creativity beginning about 100 million years ago.
We are indeed blessed that such a rich palette of sounds graces our planet and our lives. But as David warns, we are facing a potential crisis. Not only are many of us estranged and disconnected from this sensory world but we are also failing to recognize what we are missing. “When the most powerful species on Earth ceases to listen to the voices of others, calamity ensues. The vitality of the world depends, in part, on whether we turn our ears back to the living Earth.” Two fine steps in doing so: sit in your backyard and listen and read David’s book.
P.S. For those who read my newsletter last week, I trust you figured out the reference at the end. I didn’t really mean to mislead; I was just trying to have some fun and it seemed that April Fool’s Day was the best time to write it.
Plus, for those interested, I will be leading a couple of walks for the Field Trip Society in June. I am listing them now because they fill quickly.
June 11 - Stories in Stone - My tour of downtown Seattle building stone. Still popular after more than 20 years.
June 24 - Too High and Too Steep - My tour of the Denny Regrade. More fun than ever.