Cacophony on the ridge

Dr. Bob Collier
Nature notes

We get top-notch periodical publications from each of our favorite nature- and conservation-related organizations, and I look forward every month to looking through them for the newest developments and the latest findings. One that really caught my eye this past month offered me an explanation for what, to me, has become a worrisome local situation. It was in the National Wildlife Federation publication, with the clever title, “Coping with Chronic Clamor.”

Now, we’ve all heard about light pollution, the dimming of our night skies by all the lights of urban sprawl. Those of us near town can hardly see the stars any more. The Milky Way? Almost never. But noise pollution? We are actually afflicted more by noise pollution than by light pollution – the noise is with us 24 hours a day.

We’ve become accustomed to the background hum of traffic, machinery, air-conditioning and heating units, and entertainment devices. Known for a long time now to have bad effects on birds and other wildlife, it certainly affects us humans, too. We were originally designed to function in a quiet world of natural sounds, aware of what is happening around us. We are losing those skills as we are immersed in constant noise.

The Chronic Clamor article in National Wildlife? It related a series of studies on the effects of modern-day noise pollution on the lives of our birds. The first one was about saw-whet owls, little bitty guys that make their living catching mice. In the dark. By ear. The research guys found that natural-gas compression stations where they lived in Idaho could make enough noise so that the owls couldn’t hear their surroundings well enough to catch any mice at all. I can picture the maintenance guys out there scratching their heads, wondering why they’re having all those mice messing up their equipment.

Another study was from San Francisco. The people there, studying the various songs their white-crowned sparrows used to sing, found that the songs had all devolved into one, single, loud song, to enable the birds to hear each other over the noise of the traffic.

But the study that really caught my attention, because it had direct applications to us here in Knoxville, was about the effects of traffic noise along a usually quiet, remote wooded ridge in southern Idaho. Normally, migrating birds would stop on the ridge to rest and fuel up on energy-rich caterpillars, to allow them to continue flying on. The scientists rigged up a “phantom road” by placing several sets of loudspeakers along the ridge, playing traffic noise that mimicked the usual sounds of traffic in a national park. And they found that the noise caused a third of the migrating birds, unable to safely communicate with one another, to avoid pausing there in their travel – moving on, it is hoped, to a quieter place somewhere.

And how does all this apply to us here, especially the birders? Well, we have a nice wooded ridge that has been a premier spring migrant refueling stop over the years. “Bird Finding in Tennessee,” a book published by Michael Lee Bierly of Nashville nearly 40 years ago, has Tennessee birding site #85 introduced by these words: “Where in 1.3 miles can you see 28 species of warblers and 80 species of birds in a morning’s walk in May?” The answer, as every local birder would know, is Sharp’s Ridge, known more properly now as Sharp’s Ridge Memorial Park. The Ridge has always been a destination for birders, beginners to advanced. The Knoxville Bird Club has four weekly spring bird walks there, the last part of April and the first part of May. A 1992 Bird List for the Ridge, put out by City of Knoxville Department of Parks with the guidance of the Bird Club, lists 153 species of birds having been seen up there. That includes an astounding 36 species of warblers, essentially all the warblers found in eastern North America.

But as the years have gone by, the older birding veterans have seen those wonderful, warbler-filled April mornings become increasingly few and far between. We already know that our songbirds have decreased in numbers by 50, 70, 90 percent in some cases, over the past 60 years or so. These pitiful numbers are mainly attributed to loss of wintering grounds due to deforestation, and loss of food sources and nesting habitat from development and urban sprawl.

These facts certainly account for Sharp’s Ridge’s fading glory, but the article about the quiet ridge in Idaho made me wonder if the absence of the birds up there on the Ridge might not also be related to the noise up there. Sharp’s Ridge has experienced exponential increase in noise since the 1960s. All the way around the Ridge – look at I-275 on the west, I-640 on the north, Broadway on the east. And then on the south, the cacophony of Knoxville – trucks and cars, machines, trains, sirens and horns. Then there are the housing developments, condos, businesses, all marching along the sides and up the slopes, working their way toward all the communication installations strung out along the top. It’s truly noisy up there.

Of course, all of our quiet places are under pressure from things that make noise. A perfect example is the Great Smoky Mountains National Park – you would think, a place of peaceful, natural quiet. But until the Park Service put a stop to it, there were entrepreneurs up there flying helicopters into the Park to dump happy tourists off for a mountaintop picnic experience. Helicopters are about as loud as it gets.

But, just the clamor of normal daily life as we now know it to be cancels out a lot of natural sounds that we now barely remember, of have never even experienced. Somewhere in East Tennessee there is a remote, quiet, wooded ridge where, every spring, there appear waves of warblers, along with scarlet tanagers, Baltimore orioles and rose-breasted grosbeaks, resting, singing, and feeding. Quiet? It will be hard to find. I hope you’ll let me know if you do.

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