Hi everyone,

I posted this mystery recording to Twitter already, but perhaps this forum will have more ideas... 

The Forest Tuba, a #Bioacoustic Mystery:@KitzesLab found this sound in autonomous recordings (NE US forests, May/June). https://t.co/7aVfVgvxCt



We don't know what made it; our best guess is treehopper vibrational communication



Can you or someone you know ID it? Please share!

— Tessa Rhinehart (@TessaRhinehart) February 19, 2024

Over the years, my lab has deployed thousands of AudioMoths across the northeastern US to study bird communities. While using machine learning classifiers to look for owl sounds, our classifiers found some low-frequency sounds we'd never heard before and couldn't identify.

We nicknamed one type of sound the "forest tuba;" if you listen to it you'll see why. We've never been able to figure out what genus or species made this sound, but it's safe to say it's not a bird! We did get some suggestions it might not actually be audible sound, but might in fact be the vibrational communication of a planthopper, leafhopper, or treehopper. 

While we haven't been able to find a match for the "original" sound, we did find another group of sounds like this, presumably from a different species, which is a decent match for the genus Cladonata.

Does anyone else have experience with "bycatch" of vibrational communication? Are these plant-, tree-, or leafhoppers? If so, we'd love to understand why these animals decided to vibrate on (or near) our AudioMoths and if we could manage to catch more of them! The AudioMoths were deployed in plastic Ziploc bags strapped to small trees, so it's possible that somehow they thought the baggie was an extra-shiny leaf.