Foraging Behavior In Bats
My current research is taking place on Fort Campbell Military Installation along the border of Kentucky and Tennessee just Northwest of Clarksville, TN. As a part of the Haase Lab at Austin Peay State University, my project is being overseen and advised by Dr. Catherine Haase. I am currently studying the effects of perceived increased predator presence on the foraging behavior of local species.
Leah Crowley walks past a threatened tricolor bat during a cave survey
Predation has direct and indirect effects..
Not only do predators directly affect populations by taking individuals for consumption, but they can affect their behavior in ways that can be detrimental. Fear may cause them to change their foraging behavior by foraging less or abandoning fruitful sites for subpar sites to mitigate predation risk. This can have a negative effect on overall populations, but we don’t have a good grasp on how bats respond to predators. This is the study of fear driven ecology.
Bat populations are declining
Cave dwelling bats in North America have been ravaged by a fungus known as Pseudogymnoascus destructans, commonly called PD, that causes white-nose syndrome. This disease affects cave dwelling bats by forcing them to arouse too often during hibernation which makes them burn through their fat stores and starve to death.
Knowing all we can about factors influencing bat populations will be vital to their conservation, including predation.
To test the the temporal and spatial changes bats may make to mitigate predation risk we designed an experiment which will manipulate the natural environment of bats by increasing the perception that predators may be present. We accomplished this through broadcasting pre-recorded calls of nocturnal predators and using predator decoys as visual cues. Each site was sampled for two weeks, week one as control, week two as treatment.
Update, 10/13/2023
FIELD SEASON ENDED, 10/06/2023….
Over the summer I sampled 10 sites on Ft Campbell, KY, and ended up with over 250,000 data points. After running the raw data through analytic software, over 45,000 data points were identified as bats.
Plot at APSU Farm: Several plots were laid out for each site, pictured above is one that had been treated with a predator decoy and a sound box, that would broadcast predator calls at specific times.
PRELEMINARY DATA….
The following graphs are of raw data only, they are not representative of models. Models are currently being developed.
Figure 1: Graph displaying mean individual detections by treatment.
Figure 2: Presence graph that compares treated and untreated sites which are a binomial dataset on the y-axis, while on the x-axis are observations.
Figure 3: Graph representing activity in the mean number of detections at any point in time throughout the sampling window on the y-axis and time in minutes of the daily sampling period on the x-axis (1900-0000). This graph combines all detections from all ten sampling sites.
Keep checking back for updates!
*Handling bats can be dangerous. Do not try this at home! All research is conducted under the proper federal and state permits, and approved under IACUC 23.008 from Austin Peay State University. Members of the lab have been properly trained and immunized to handle chiroptera species.