Yesterday I began to think again about the acoustic niche theory, the idea that animal and insect species communicate by making sounds in distinctive niches according to frequency, timbre, and time. This supposedly enables them to communicate with one another, and without interference from the sounds of other species. Out on my (almost) daily walk, I'd heard a bird whose song reminded me of the yellow warbler, but I knew that it would be highly unusual for one to be here at this time of year. Trying to make a recording of this bird’s song, I got annoyed when two crows began cawing and interfering with my clear recording of the mysterious bird (who was, also, out of sight). And in the far background I heard the occasional whine of a chainsaw in the act of cutting; I could scarcely hear it when it was idling.
The mystery bird seemed to begin its song in the silence, but before it was over the crows began to caw, almost as if they meant deliberately to interfere with my recording, if not with the bird's song. I thought they might decently wait for a moment of silence on behalf of one of their fellow creatures, if not for me, and then begin their cawing—but they didn’t wait. Out of about 90 seconds I was able to get only one clear recording of a song from the mysterious bird, lasting about three seconds.
The mystery bird seemed to begin its song in the silence, but before it was over the crows began to caw, almost as if they meant deliberately to interfere with my recording, if not with the bird's song. I thought they might decently wait for a moment of silence on behalf of one of their fellow creatures, if not for me, and then begin their cawing—but they didn’t wait. Out of about 90 seconds I was able to get only one clear recording of a song from the mysterious bird, lasting about three seconds.
I wondered, then, whether the birds might have been disturbed by the chainsaw, which was sounding continually, although softly when idling. Bernie Krause's recordings of the sounds of tropical rain forests reveal that after an airplane flies overhead, the soundscape is altered. That is, before the airplane, the sounds seem to repeat in cyclic equilibrium; but after the airplane and its noise has come and gone, the sound equilibrium is no more, and it takes a few minutes for the creatures to get back into it. Or, perhaps, the mysterious bird sang long enough to communicate what was necessary, and that the crows coming in over the end of it—much more loudly—didn’t really interfere. (What could interfere with a crow’s cawing, I wondered?)
I recalled certain times of day in spring, such as dawn and dusk, when many birds sing more or less at the same time. The acoustic niche theory cannot possibly hold that birds take turn filling the silence. I suppose it is enough that each species can identify its kind by close listening to song melody and timbre. But I wondered, still, about the chainsaw.
I recalled certain times of day in spring, such as dawn and dusk, when many birds sing more or less at the same time. The acoustic niche theory cannot possibly hold that birds take turn filling the silence. I suppose it is enough that each species can identify its kind by close listening to song melody and timbre. But I wondered, still, about the chainsaw.
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