Abstract:
The extensive forested uplands of Morgan-Monroe and Yellowwood State Forests (MMYSF) in
southern Indiana are largely composed of ephemeral streams. The Indiana Department of Natural
Resources created ponds within the state forests to provide year-round fresh water for wildlife.
The goal of this study was to document bat activity at these ponds, and determine what habitat
attributes influence bat activity levels. In 2018 and 2019, we conducted acoustic surveys at 25
ponds, and temporally paired sites in the surrounding forest, during the summer months.
Vegetation structure surveys were conducted at each pond to quantify habitat attributes that
could affect bat activity, and aquatic faunal surveys were used as a surrogate for water quality.
Results showed that bat activity was significantly higher at ponds than forest sites. A two-way
ANOVA revealed that only two of 25 ponds surveyed had significantly more bat activity than
the average, and results were consistent between years. According to a random forest model, the
amount of vegetation surrounding ponds had the strongest relationship with bat activity
compared to the other variables. Ponds with the highest bat activity had the following
characteristics: < 35% vegetation structure surrounding the pond, surface area ≥ 1000 m2, and
surface area coverage with emergent vegetation between 40-60%. In 2019, a small treatment
experiment was conducted on a subsample of three ponds that were the least active in 2018, and
two random selected ponds, not previously surveyed. Four 11m x 2m flyways were created
around each of the five ponds by removing midstory trees and shrubs, to test if lowering the
amount of vegetation surrounding a pond would increase overall bat activity levels. We used a
two-way ANOVA with repeated measure and observed no difference bat activity levels between
acoustic surveys, suggesting that bat activity is influence by other habitat attributes, in addition
to vegetation structure. However, there were multiple outside influences within this single year
experiment that may have influenced our results.
