Effects of Trophic Pressures on Nocturnal Activity in Wisconsin Microbats (Chiroptera: Vespertilionidae)

Grace Wampole, Kyle Bergendahl, Zachary Williams, Mitchell Anderson, Shannon O’Malley, Dr. Catherine Mossman, Dr. Jessica Orlofske, Department of Biological Sciences, University of Wisconsin - Parkside, 900 Wood Rd, Kenosha WI 53144

Bats are susceptible to opposing ecological pressures as both prey and predators. “Lunar phobia” may decrease bat activity time during periods of strong lunar illumination to avoid predation by raptor species. However, many insects are positively phototactic and exhibit greater activity with lunar illumination. Bats must respond to these conflicting pressures. We predicted a positive correlation between bat and insect activity during the first and third quarter moon phases with strong negative correlations during the new and full moon. To test this, we collected paired arthropod samples and bat recordings at dusk for nine 60-minute sampling events between May-August 2019 at two wooded sites in Racine Co., WI. Quantitative arthropod samples were collected using light traps at both sites. Bat calls were recorded using a Baton bat detector attached to a voice recorder. Bat call analyses were completed using the freeware program, Audacity. The recordings were assessed and cleared of background noise in order to quantify the number and duration of each echolocation call. Arthropods collected were identified to family using taxonomic keys and cross-referenced to publications on bat diet and foraging behavior to evaluate food quality. Using a Pearson correlation, there was a strong positive correlation (64.11%) between insect richness and percentage of microbat activity as well as a positive correlation (56.95%) between bat activity and percentage of the moon visible for each date which is contrary to the “lunar phobia” hypothesis. We observed a trend in increased microbat activity when there was an increase in arthropod richness and abundance; however, more data is needed to address outside factors. Understanding how bats and their insect prey respond to natural illumination can be used to predict the impact of light pollution on food web dynamics.

Additional Abstract Information

Presenters: Grace Wampole, Kyle Bergendahl

Institution: University of Wisconsin - Parkside

Type: Poster

Subject: Ecology

Status: Approved

Time and Location

Session: Poster 5
Date/Time: Tue 12:30pm-1:30pm
Session Number: 4118