Co-author on paper on how river noise affect webs and prey capture of orb spiders

I’ve been involved in a side project of the very promising PhD student Dylan Gomes from Boise State University in Idaho, who contacted me a few years back asking for help on how to extend his work on the ecological affect of river noise on vertebrates to orb spiders. I have had the pleasure of being peripherally involved in this project, which now after three years of data (collecting data from 190 webs and 947 prey capture events) has been published in Functional Ecology. Playback and natural river noises were used to show that higher sound pressure levels from streams increased abundance of both the tetragnathid Tetragnatha versicolor and the araneid Larinioides patagiatus, but decreased web size for tetragnathids while not affecting the araneid webs. Interestingly, the capture of dipteran prey increased for the tetragnathid while it decreased for the araneid.

While these effects are likely to have arisen from indirect effect via the effect on prey and predators (birds and bats), direct spider responses to river noise cannot be ruled, although clearly more research is needed to tease out the reason for the complex and contrasting responses in the two spiders.

Gomes, D., Hesselberg, T. and Barber, J. Phantom river noise alters orb-weaving spider abundance, web size, and prey capture. Functional Ecology, In Press. https://doi.org/10.1111/1365-2435.13739

Novel anthropogenic noise has received considerable attention in behavioral ecology, but the natural acoustic environment has largely been ignored as a niche axis. Using arrays of speakers, we experimentally broadcasted whitewater river noise continuously for three summers, and monitored spider abundance and behavior across 15 sites, to test our hypothesis that river noise is an important structuring force as a niche axis. We find substantial evidence that orb‐weaving spiders (Araneidae and Tetragnathidae) are more abundant in high sound level environments, but are not affected by background noise spectrum. We explore multiple possible mechanisms underlying these patterns, such as loss of vertebrate predators and increased prey capture, and assess spider web‐building behavior and body condition in noise. Continued research on the natural and anthropogenic acoustic environment will likely reveal a web of connections hidden within this neglected ecological niche axis.