Dylan Gomes, a Ph.D. candidate at Boise State University, explains to us how the sounds of water affect spider abundance and behaviour in the recently accepted article, “Phantom river noise alters orb-weaving spider abundance, web size, and prey capture”, and discusses the need for more acoustic research in the field of ecology.

  • What’s your paper about?
Lead author (left) setting up a speaker tripod for whitewater river noise playback.
Lead author (left) setting up a speaker tripod for whitewater river noise playback.

Our paper highlights the importance of the natural acoustic environment in animal behaviour and ecology. We have begun accumulating a lot of evidence of what human-made noise does to wildlife, but we do not know much about how natural sources of noise might influence animal populations or shape communities. While orb-weaving spiders are not typically considered acoustical creatures, we show that experimentally broadcasting whitewater river noise drastically increases the number of orb-weaving spiders in our surveys, and those spiders build smaller webs. This suggests that likely many organisms are affected by the acoustic environment.

  • What is the background behind your paper?

Animal behaviourists and ecologists have long appreciated that animals perceive the world differently from one another. The idea of an umwelt, or an animal’s perceptual world, has been around for over 100 years. However, humans have biases when it comes to sensory perception. Observation, a crucial component of the scientific method, is thus filtered by these biases. We believe that the acoustic environment has been largely ignored as an ecological niche axis because of our strong connection to visual perception. This is one reason why we are so excited to explore how wildlife is affected by acoustics.

  • Does this article raise any new research questions?
A female orb-weaving spider (Larinioides patagiatus) near a web retreat.
A female orb-weaving spider (Larinioides patagiatus) near a web retreat.

It is not clear what is driving the patterns we see here. Are spiders attracted to the noise? Is river noise a habitat selection cue, increasing spider numbers? Or are spiders simply surviving longer because predators avoid the noise? We know that insectivorous birds and bats (which often eat spiders) avoid human-generated noise, but there are no published data on how they respond to natural river noise – although we are currently working on publishing these data!

About the research

  • Why is it important?
An orb-weaving spider web after the spider has been collected.

Our streams are an important resource that we manage. As we dam rivers, we are altering the background acoustic environment. Dams create quiet, placid lakes or slow-moving rivers upstream and intense falls and cascades downstream of spillways. Dams allow us to alter temporal patterning of streamflow by delaying run-off until later in the year. We know that dams can alter stream flow, temperatures, and sedimentation rates, which all impact local flora and fauna, but this work highlights that the acoustic environment itself can disrupt ecological systems. We do not know much about how these changes to the acoustic environment impact wildlife, but this is important to understand as we continue to alter natural acoustic environments and replace them with human-made ones.

  • Did you have any problems setting up the experiment/gathering your data?

We hiked almost four tons (~3300 kg) of acoustics gear into the Pioneer Mountains of Idaho, a place that might get 60 mph (~27 m/s) winds, hail, or snow on any day – even during the summer. This in itself was sometimes a rough process, but we also had flooding snowmelt wash out an access road, bears attack our recording devices on multiple occasions, and one of our batteries catch on fire. In just one of the summers we had 9 flat tires between all of our research vehicles. A project this large was destined to have some failures, but it worked out in the end!

  • Were you surprised by anything when working on it?

We were not terribly surprised by any of the data, but I was surprised many times by ungulates – mule deer and moose – while working at night on these nocturnal spiders. The darkness takes away your ability to see and the speakers broadcasting river noise take away your ability to hear. This leads to many scary encounters with wildlife. We have seen plenty of bears and mountain lions in the area, which is also known to have packs of wolves, so the work lends itself well to being hypervigilant at every step.

A suspended speaker broadcasts intense river noise near a small stream. The solar panel charges batteries that power the speaker throughout the day and night for months each year.
A suspended speaker broadcasts intense river noise near a small stream. The solar panel charges batteries that power the speaker throughout the day and night for months each year.

About The Author

  1. What’s your current position?

I am currently a PhD student at Boise State University working with Dr. Jesse Barber. However, I hope to finish my dissertation soon because I have recently informally accepted a postdoctoral research position with Oregon State University and the National Oceanic and Atmospheric Administration (NOAA) in Oregon that I plan to start in March.

  • What is the best thing about being an ecologist?

We get to spend our time exploring the depths of the natural world. There is nothing more beautiful or interesting than the world around us.

  • What do you do in your spare time?
The lead author hiking from one site to another in the Pioneer Mountains of Idaho.
The lead author hiking from one site to another in the Pioneer Mountains of Idaho.

I am always outside. I enjoy mountain biking, snowboarding, birding, fishing, hunting, backpacking, working on the garden, woodworking, and finding spiders under bridges. Anything hands-on and outside!

  • One piece of advice for someone in your field…

Just keep swimming. Anything that can go wrong eventually will, so you have to have the determination to push through it. If you work hard and continue to grind away, good things will come.

Read the article in full here.

Read more about Dylan Gomes’ research on his website