Here they are! It is finally hot enough for the cicada choir to crawl out of the soil and shake our senses with their sunlight-made-into-sound, a concentrated celebration of a dozen years of Tennessee’s lush photosynthesis.
Early in the morning, they start with the waaaa-oo waaaa-oo chorus call from the treetops. As the day heats up, their raspy courtship calls dominate, interspersed with the wing-clicking of females.
You can hear both the ghostly waaa-oos and the louder rasps in this recording that I made with a Zoom H4:
So far, the thirteen-year cicadas have been much more active in the valley than on the mountain. There are a few buzzing around Hat Rock Rd and Willie Six Rd, but most places in Sewanee have no cicadas. They may still be on their way, the soil here being cooler than in the valley. However, thirteen years ago the cicadas were also much less common in Sewanee/Monteagle than in the lower surrounding areas.
…is how loud the 13-year cicadas were when I made a pilgrimage to Sweeten Cove to listen to them this afternoon. The CDC recommends that humans limit their exposure to any sound louder than 85 dB. I can see why — my ears were ringing after spending half an hour in the midst of a cluster of cicadas.
Thirteen-year cicadas pulse the loudness of their sounds every four or five seconds (top graph). Their hissing, buzzy sound is concentrated in the middle and high ranges (bottom graph; for comparison, humans talk below 1 kHz). I made these recordings standing under a hackberry tree that was swarming with cicadas, then used Raven to draw the graphs.
Newly emerged cicada in Sewanee, TN. May 12, 2011. Genus Magicicada
The cicadas have been underground for thirteen years, feeding on the sap of roots. Now, the concentrated power of all those years of photosynthesis is unleashed in their songs. Their massed buzzing turns into a roar that penetrates buildings and overpowers conversation.
Around Sewanee, these insects are much more common in the valleys and low mountain slopes than they are in the uplands. Presumably, the cicadas thrive where the soil is deep, rich and full of well-provisioned plant roots.