The hermit thrush sings one of the most beautiful songs in the Northwoods. Sometimes in evenings I’ll walk just to hear those liquid notes coming from the leafy green darkness of the woods. Mornings too, if I have the opportunity. One is singing in the forest beyond my window as I write this.
In The Singing Life of Birds, ornithologist and dedicated bird song aficionado Donald Kroodsma spent some time studying the songs of these birds. Many people may be surprised to know that songbirds, like the hermit thrush, have a method of singing that unites them, that identifies them as being what songbird they are, but the individual birds themselves develop their own unique songs.
Similarly, in the human world different cultures have different languages. In fact, we pride ourselves on our language ability which has indeed produced amazingly intricate and elaborate sounds. These languages are identifiable by the sounds that make up that language’s repertoire. The !Kung speak with clicks integrated with their words. German is often described as guttural. Chinese has a lilt and rhythm. On top of these differences, individual speakers within each language have their own style and choose what words from their shared language to say at any given time.
Even the same language can sound quite different when spoken by people from different regions. British English is quite clipped. The Irish speak English with a lilt. The American South is known for its easygoing drawl.
Interestingly, birds within the same species have dialects as well. As Kroodsma writes, chickadees, for example, have slight variations in their “phoebe” calls depending on where in North America they are from. This has to do with the fact that, like humans and our own languages, songbirds learn their songs from their family and community. In fact, if we were to step back and look at humanity from the perspective of another species, would our languages sound as similar as the North American chickadees does to us? What are the similarities in human languages that make them generally identifiable as human speech?
But back to the hermit thrush. Each male, according to Kroodsma, averages about 15 different songs. The thrush will cycle through these 15 different songs, which can take quite a while, and then usually start the cycle again.
If you listen to each song within the cycle, you’ll notice how the thrush varies his phrases within the song. If his first phrase is lower pitched, the second will be higher, the third lower, the fourth higher and so on. Occasionally within the song he’ll make a bridge phrase that is higher than the previous but lower than the next. Or vice versa. It’s fascinating.
Too abstract? Let’s draw from the real world then, if you like, by listening to this recording. In recording it, I didn't use a professional parabolic birdsong recording microphone or anything, but I think the pattern of high-low musical variation will become apparent right away.
The question, of course, behind all this is: what are they saying? I think we may perhaps be able to decipher the most general of interpretations for each songbird species as a whole. But what is each individual saying in the details? Is it a story of the last year? Of their life? A description of their territory? The oral history of their family? I doubt we’ll ever know, and I hope in that not knowing we don’t pretend there isn’t something to know.
Besides the mystery can be just as beautiful as the knowing.
Sometimes more so.
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