Predation risk affects group formation of mammals in Upstate South Carolina
Elisabeth Howansky and Zachrey Swartzentruber
*Winner of the Judges’ Choice Award*
Mammals may form groups to access resources, care for offspring, and avoid predation. We hypothesize that in Upstate South Carolina predation is a driving force for group formation. Consequently, we expect groups will be more common in vulnerable prey species than they will be in mammals with lower predation risk. We predict mammals will also be more likely to form groups in open habitats where they are visible to predators. Finally, because temporary human disturbance (THD) has been observed to have a similar effect on mammals as predation, we predict that group formation will be more common when human disturbance is high. To test these hypotheses, we collected data using camera traps at sites with varying levels of human disturbance that include forest, edge, and open habitats. The photos captured were labeled by species and number of individuals. We used a Fisher’s exact test to analyze the data collected from the images within each category (predation risk, habitat openness, THD). Groups were most frequently formed in mammals with the highest predation risk (p<0.0001), but mammals with medium to low predation risk were not significantly different in their group formation. Group formation was most common in open habitats and least common in forested habitats (p<0.0001). Any amount of human disturbance also caused group formation to be more common (p<0.0001). As predicted, groups are formed most often in prey species, in open habitats, and in areas with any human disturbance. Our results support the hypothesis that mammals form groups in response to the threat of predation.
Elisabeth Howansky, better known as Elisa, is a junior biology major pursuing a career in biostatistics. They are a member of the Lander University Honors College and the Psi Theta chapter of TriBeta National Biological Honors Society.
Zachrey Swartzentruber is a senior biology major. He is a member of the Tribeta National Biological Honors Society and plans on pursuing a career in marine or ecological sciences.