“Excuse me,” says a quiet voice to my right. “But what is a glowworm?” “The glowworm is a beetle,” responds our sage. “We’ve only got one species in Britain. They belong to the firefly family. This one’s strategy is rather simple: Large flightless females emit light with the aim of attracting males.”
“So, shall we go and see some?”
I had imagined that the next bit would take some time. That, like all good nature-writing stories, we would search and search and then search some more, and then, just as we were packing up, we’d see one: glowing like a beacon, a single revolutionary invertebrate in a world lit by artificial coal-fired lights. Our glowworm. We’d whoop for joy, hug, weep with the wonder of it all. But no, it wasn’t quite like that.
It happened like this: We turned a corner, looked at the first long bank of vegetation and saw them, five or six twinkling stars in the grass. And that’s the first thing you need to know about looking for glowworms — it’s remarkably easy. Look for little points of light, then, well . . . walk toward them.
Within what seems like seconds, small clusters of five or six people bend over each ghostly green point of light. I head toward the nearest. Someone shines a flashlight right into the beetle’s appendage-laden face. Even with the full beam on her, the glowworm continues pumping out her green charge, illuminating the strands of birdsfoot treefoil on which she clings. She is like an elongated woodlouse, and about three times the size. Her tapering tail is waggled over to one side, and it is from the final three segments that the ghostly glow emanates.
We amble in our own little clusters from this point on, homing in on more tiny, glowing, green bottoms among the undergrowth.
“And were they once everywhere in Britain?” asks someone to my left. David chews on this for a second. “Yes . . . they were once probably everywhere,” he says, before mulling over a thought in his head. “I’d quite like to contemplate the impact on male glowworms of all of the streetlights,” he adds quietly, looking at the reflected streetlights bouncing back off the clouds above. Those who heard him say it stand silent there, thinking about this for a few seconds. “Streetlights?” someone from behind me says.
“The trouble is, the males probably go and mate with the streetlights rather than mate with the females.” They do what? “Is that why they’re declining?” someone asks to my right. “Well, it might be,” offers David.
I stood there and imagined what a streetlight must look like to a male glowworm. Impossibly long strip, sultry red tone, that irresistible sexy hum. The males drawn in on tractor beams, flying straight past the females. I picture their final hours, bashing-bashing-bashing against a panel of illuminated glass until they expire or succumb to a passing bat. Poor little suckers. It was the first time I had ever really consciously imagined that human actions, human insight, human ingenuity, human technology, could mess up the sex life of another animal. Are we civilized folks becoming nature’s cold shower? Predictably, the answer is yes. And not only are some aspects of nature’s sex taking a battering; in some cases, it might actually be fighting back, modifying its advertising to be better heard over humanity’s din.
Nature Fights Back
Roads are one such battleground. It appears that here, natural selection is working at a rapid rate. And beside these roads, grasshoppers are becoming the study species of choice. At least some are adapting to the ruckus.
Grasshoppers make their calls by scraping rows of tiny pegs on their back legs against a thickened vein on the forewing. Each grasshopper species has its own call, simply determined by the number of tiny pegs and the rate of this “stridulation.” Because grasshoppers often share habitats with a number of other grasshopper species, natural selection has driven each to stand out from the others when calling. When comparing populations of bow-winged grasshoppers from locations near busy roads with those away from roads, some German scientists in 2012 spotted a few key differences. They found that some grasshoppers from noisy habitats try to boost the low-frequency parts of their song to get their voices better heard against the low-frequency drone of traffic. Nature is fighting back, and the low frequencies are the battle lines. In fact, the low-frequency parts of other animal songs appear to be similarly vulnerable to the blaring noise of road traffic. In early 2013, a Canadian study showed that the presence of lower-frequency elements in a song could be used to predict, to a degree, the abundance of songbirds setting up shop near a road. In human terms, it seems that low-frequency singers lose patience with roads and think, “Screw this: I’m off to somewhere quieter.”