In the San Juan Basin of New Mexico, far from human habitation, there is a cacophony of man-made noise. The Basin is the nation’s second-largest natural gas field, and for miles in every direction, gas compressors are running more or less constantly, filling the desert with their eerie, broadband roar.
When compressors are built near where people live, the machines, which can range from the size of a pickup truck to the size of a house, are surrounded by walls to help dampen the sound. But creatures that live in the desert are not so lucky. Research has already shown that bats and birds behave differently in areas with loud noise, including where compressors are running. Now a team of ecologists has found that bugs are shaken up by compressors, too—and by high decibel levels of noise in general.
For the study, the researchers buried small ethanol-filled containers in 10 sites around the gas field: five with compressors and five without. Even sites without compressors could be loud, as they were all situated within earshot of machinery. The researchers kept track of the decibel level at each plot, and every other day for two weeks, they retrieved bugs that had fallen into the ethanol traps, accumulating more than 1,700 across all the sites. Then they worked to classify the bodies—a range of arthropods including ants, leafhoppers, spiders, and crickets—into families and genera.
Very quickly, patterns emerged. “When we started doing the identification and looked at the data in its raw format, we realized there were some interesting trends going on,” says Jessie Bunkley, who led the research as a Boise State University graduate student. Some bug groups did not show much difference in abundance regardless of the overall noise level or the presence of a compressor. But others had dramatic changes. There were 24-percent fewer grasshoppers in compressor plots, 52-percent fewer froghoppers, and a whopping 95-percent fewer cave, camel, and spider crickets. The louder the plot was, regardless of the presence or absence of a compressor, the fewer velvet ants and wolf spiders there were.
Why are these particular bugs seen less? It isn’t clear, though they all do come from groups that are known to respond to sound or vibration in some way, whether from the ripples in a web as a trapped fly struggles to free itself or the stridulating song of a mate. Compressors create a curiously oppressive noise, with both high and low frequencies at very high volume, running 24 hours a day, seven days a week, nearly 52 weeks a year. More so than traffic noise, which might peak at certain hours of the day and then drop off, compressor noise may significantly affect the surrounding ecology when the inhabitants are sensitive to sound. And the effect might not be as simple as crickets steering clear of the machines. Animals that prey on insects, like bats and birds, could alter their behavior as well, catching more of one kind than another when the compressors are there, for instance.
There was one group in the study, the leafhoppers, whose numbers actually increased in the presence of a compressor. Some insects, including mosquitoes and midges, can be attracted by certain sounds, says Bunkley, so it’s possible that the compressor is sending a message to leafhoppers, which can use vibration for locating mates: “It could be a situation where it’s a sensory trap, where they’re responding to a signal on the landscape with their instinctual response of ‘okay, I'm attracted to this vibration—it means mates.’ And in reality it’s just a giant machine.”
These alterations in the kinds of invertebrate life near noisy human machinery are reminiscent of how, in another sensitive environment, the noise of ships, oil exploration, and military sonar disrupt the communication of whales, causing them to grow disoriented and die on beaches. There has been quite a bit more research on that phenomenon than on the effects of gas compressors and wildlife. “Certainly this paper is just the very tip of the iceberg,” says Bunkley, when it comes to understanding how desert ecosystems change in response to noise. But whether in the ocean or the desert, it seems we can’t escape the sounds of our own devices, and neither can all the creatures that live alongside us.
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