The Influence of Natural Sounds on California Ground Squirrel (Otospermophilus beecheyi) Vigilance and Predator Detec on Christopher M. Garvin1, My-Lan T. Le1 and Dr. Clinton D. Francis1 1California Polytechnic State University, San Luis Obispo, San Luis Obispo, CA 93407 Background Behavior Trials Coyote Detec on Trials o These trials involved 5 minutes of constant observa on. The California ground squirrel is a social o This trial tested squirrels’ ability to o Behaviors were separated into 11 categories: vigilant on two legs, vigilant on detect an incoming predator with animal that lives in burrows. Colonies range in size from four legs, foraging and vigilant, foraging, moving, social, grooming, res ng, dust a few individuals to dozens. Living in colonies bathing, digging and tail flagging. or without the addi on of sound provides protec on from predators such as o Time spent performing each ac vity was converted to a percentage spent to the environment. hawks, coyotes, and ra lesnakes. For protec on, performing each ac vity. o A robo c coyote was made by
colonies usually have a sen nel that is vigilant combining a RedCat Racing Rock Crawler and a coyote decoy.
for predators. Addi onally, each squirrel must weigh the risk of foraging Focal Individual o The robo c-coyote started 50m
versus being vigilant so they can be er detect incoming predators. During this trial, a single individual was observed for the dura on of the test. away from the focal squirrel. Using a spo ng scope, this individual was randomly selected from the Many factors affect how a ground squirrel behaves, but in this study o It was driven at a steady pace we are looking at how a changing soundscape affects their behavior. visible popula on. toward the squirrel to simulate the This is relevant because the sound- Results: 100 hun ng style of a coyote. scape of the US has changed dras cally o There was not a significant Results o The Flight Ini a on Distance (FID) difference between the 80 was recorded. due to human ac vity. This change is o This plot shows that the FID was me individuals spent not significantly different causing the behavior of prey species to 60 vigilant for the control and 1 depending on the treatment. 4.0 change . In par cular CA ground insect (cicada) treatment. 40 This is not what our predic ons squirrels become more vigilant and o o However, during the river % Total Vigilance and hypothesis expected.
forage less in response to increased 3.0 trials individuals spent 20 o Factors that are more important 2 anthropogenic (human-induced) noise . significantly more me in determining FID are: log(FID1)
0 However, it is not known how vigilant for predators. • distance of squirrel to its
2.0 o Other important factors: Control Insects River natural sounds affect the behavior of burrow Soundscape of changes of noise level in • Average group size squirrels. The intent of this study is to Treatment • number of other squirrels the United States. Brighter colors indicate • Group composi on 1.0 explore this rela onship. a greater increase in ambient noise. present • Composi on of surrounding Control Insects River Group colony Basic Design Treatment This trial was done simultaneously with the individual trial. A scan of all o This experiment will use 3 treatments to test the effects of natural sound on behavior: visible squirrels was performed every 30 seconds and each individual’s • Cicada Calls (low frequency) behavior was recorded. Discussion • Rushing Water (river noises, high frequency) Results: 2.0 • Control (a “no energy” track played on a speaker to control for EM energy) o These ini al results are cryp c and o These natural sounds are broadcast ~ 50 meters away from a colony at the level of 85 o There is very li le difference dBFLT at 1m between the three further analysis is necessary.
• Squirrels thus experience a biologically relevant s muli of 50-80 dBFLT3 treatments. 1.5 o Squirrels do not respond to high o Inves gators were 30-50m away from the colony in a hun ng blind to hide their presence o This suggests that other frequency noises (cicada). o 9 colonies were chosen for tes ng variables are more important o Squirrels respond more consistently to o Each colony underwent 3-6 tests 1.0 in determining group • 1 test for each of the three sound condi ons- cicada, river, and control / Vigilance Foraging low frequency noises (river). • If possible each of these three condi ons was completed once with adults behavior than the noise o Many variables besides the sound level and once with juveniles treatments. 0.5 contribute to squirrel behavior, notably o These variables include: Control Insects River the average group size, group • Average group size • Treatment composi on, and age of the individual. Hypothesis Group composi on An increase in natural noise will increase the vigilance of the California ground squirrel. Predic ons: References o Individual and group of squirrels will spend less me foraging and 1. Shannon, Graeme, et al. "Road traffic noise modifies behaviour of a keystone species." Animal Behaviour 94 (2014): 135-141. 2. Rabin, Lawrence A., Richard G. Coss, and Donald H. Owings. "The effects of wind turbines on an predator behavior in more me vigilant when exposed to natural sound treatments. California ground squirrels (Spermophilus beecheyi)." Biological Conserva on 131.3 (2006): 410-420. 3. Francis CD, Barber JR (2013) A framework for understanding noise impacts on wildlife: an urgent conserva on priority. o Squirrels will be quicker to flee from a perceived predator as a result Fron ers in Ecology and the Environment 11, 305-313.
of increased vigilance when exposed to natural sound treatments. The 2017 STEM Teacher and Researcher Program and this project have been made possible through support from Chevron (www.chevron.com), the Na onal Marine Sanctuary Founda on (www.marinesanctuary.org), the Na onal Science Founda on (www.nsf.gov) and the California State University Office of the Chancellor, in partnership with the California State University of San Luis Obispo.