Date of Award

12-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Forestry and Environmental Conservation

Committee Member

David S. Jachowski, Committee Chair

Committee Member

Kyle Barrett

Committee Member

Susan C. Loeb

Abstract

White-nose syndrome (WNS), an infectious disease that has caused massive declines in bat populations since its discovery in 2006, may be indirectly affecting bat community structure. As WNS-susceptible species populations decline, WNS-resistant species may be taking over foraging niches formerly occupied by WNS-susceptible species. We hypothesized that bat communities located in WNS-positive areas in South Carolina have experienced niche partitioning relaxation. First, because some pre-WNS acoustic data were collected using different methods than those primarily used today, we examined if sampling method affected detection probabilities and our interpretation of habitat use of bats. We collected data using passive and active techniques in July 2017 at the Savannah River Site in South Carolina. We used occupancy modeling to determine if data collection method influenced detection probability of bats. We found that method had a significant effect on detection probabilities of all species and that passively sampling throughout the night yielded the highest detection probability. To further examine if data collection method influenced habitat use conclusions, we used occupancy modeling to analyze data collected passively in July to August 2016 and July 2017 and compared our results to a historical study in which active acoustic sampling was used at the same sites in 2001. We found that some parameters had the same effect between studies for some species, while other parameters had a different effect between studies. We concluded that data collected using different methods was not comparable. Second, revisiting a WNS-positive site where passive acoustic sampling was conducted historically, we examined the extent to which spatial and temporal niche partitioning occurred pre- and post-WNS. Specifically, we collected data using acoustic detectors from May to August 2004 and 2005 (“pre-WNS”) and from May to August 2016 and May to June 2017 (“post-WNS”) in the Andrew Pickens District (APD) of the Sumter National Forest in northwestern South Carolina. To examine changes in the spatial niche partitioning of the bat community, we used multi-season occupancy modeling and examined colonization and extinction probabilities. To examine temporal niche partitioning, we examined bat activity throughout the night using temporal overlap analysis. We found that the WNS-resistant species had higher colonization rates than WNS-susceptible species and changed their nightly activity so that it was more evenly distributed throughout the night post-WNS. Myotis, a WNS-susceptible genus, stopped using areas in hardwood habitat and changed when they were active at night post-WNS. Tricolored bats, a WNS-susceptible species, exhibited changes in the areas they were using, though this did not seem to be contingent on the presence of other species, and did not change when they were active at night post-WNS. These results provide evidence that WNS destabilized the spatial and temporal niche partitioning exhibited by bats pre-WNS in South Carolina and further evidence that WNS is both directly and indirectly affecting the bat communities in North America.

Share

COinS