If you’ve seen a person walking through campus with a bright yellow kitty litter bucket in hand and who pauses to stare intently into a tree in front of your building, you might have thought they were a birdwatcher or maybe just part of the local color.
But that person is not merely staring into a tree and their yellow kitty litter bucket is not filled with kitty litter. What you’ve probably seen is a member of the Squirrel Squad in action.
The Squirrel Squad is a group of student researchers working with Keith Tarvin, Professor of Ornithology and the Chair of the Biology Department, to study the interaction between squirrels and birds: specifically, how squirrels eavesdrop on bird chatter.
The Squirrel Squad consists of Oberlin third years and Biology majors Eli Haines-Eitzen, Abby Parker, Larissa Michel, and Natasha Radic. Although they are not the first students to assist Tarvin in his research, the affectionate name for the group is their own.
Each week, members of the group venture into Oberlin’s neighborhoods, arms laden with recording equipment in their distinctive yellow buckets, to observe how eastern gray squirrels react to select bird noises.
“Squirrels use bird chatter to determine the presence of predators. If there is a lot of bird chatter, squirrels decrease their vigilance behavior, or their alertness, because they know that it’s probably safe,” explains Eli Haines-Eitzen. “If there is no bird chatter, squirrels are more vigilant because they don’t have anything to gauge the threat level.”
Tarvin uses the analogy of a concert hall to explain: if you’re in a concert hall and everyone is talking and then suddenly stops talking, you’d look around to see what is going on.
For each trial, students locate a squirrel, set up speakers, and play bird calls to study the squirrel’s reaction. The trials are five minutes long and begin with one minute of acclimation and no bird sounds or data collection, followed by thirty seconds with no sound, but with data collection to establish baseline vigilance, and then three and a half minutes with bird sound where squirrel behaviors are monitored.
The group plays one out of five categories of bird noises: ambient noise, foreign chatter, local chatter, local song, and unfamiliar song. The Squirrel Squad is also researching to see how squirrels react to foreign versus local bird sounds.
They are hoping to find out “whether squirrels treat chatter as a class of information or if they listen to specific, local species of birds, and to hone in on how animals listen to each other and the importance of sound as well,” says Abby Parker.
The research is ongoing, but the Squirrel Squad has noticed a level of interest and attention that squirrels pay to unfamiliar calls. “I did a trial recently with unfamiliar calls and the squirrel was definitely interested in what was going on. His tail was twitching and moving back and forth.” Natasha Radic recounts. She adds, “I see a lot of variation in how much squirrels respond to different calls.”
The squad observes six squirrel behaviors. “Foraging, preening, and resting are considered low vigilance states, while freezing, standing, when squirrels stand on their hind legs, and fleeing are high vigilance behaviors,” says Larissa Michel. They use an app designed by Tarvin to note the occurrence and duration of each behavior during their trials.
Public information such as bird sounds, which are available to any organism capable of processing noise, plays an important role in community ecology and interspecies relationships.
The relationship between eastern gray squirrels and bird chatter, as well as interspecies relationships in general, may seem insignificant to those not familiar, but has greater implications for wildlife as human development spreads across the globe.
“With increasing urbanization it’s important for us to know how much animals rely on sound in their environment so we can be cognizant while planning cities,” says Parker. The nature sounds humans observe in passing, like bird calls, play essential roles in the lives of other species.