Date of this Version
Fill, Christopher, "Spatial and Temporal Patterns of Bat Activity in a Southeast Nebraska Agricultural Landscape" (2020). Dissertations & Theses in Natural Resources.
Intensive agriculture is associated with biodiversity loss and species decline. Yet wild species, such as bats, may provide critical ecosystem services to agriculture, even in transformed landscapes. In the United States, bats have been estimated to save the agricultural industry billions of dollars per year. However, white-nose syndrome and habitat loss have led to the decline of many bat species in North America, including the federally threatened northern long-eared bat, Myotis septentrionalis.
To better evaluate the effectiveness of these pest-controlling services, and to increase understanding of bat foraging behavior in these extreme landscapes, I deployed 11 grids of 24 detectors, in 6 x 4 formation, 100 m apart in crop fields bordering different edge habitats, sampling each once over a period of four nights. Bat activity was highest at sites with the most wooded edge habitat, and sites with more trees and water typically had the most species diversity. While bat activity and species richness were low at isolated habitat fragments and sites with minimal habitat edges, overall insect availability remained abundant in fields as by field edges, suggesting less hunting pressure on insect pests in these areas. I found high degrees of species temporal overlap and failed to detect any significant negative spatial or temporal relationships between species.
I also conducted capture and tracking surveys for threatened northern long-eared bats at Homestead National Monument of America to document roosting behavior at the western edge of this species range. I tracked two individuals to rooting sites, each bat using multiple structures, one selecting trees and snags two miles upstream of the park, and another using tree cavities and shadowbox fences in the park with other untagged northern long-eared bats. These results suggest that wooded areas, riparian zones, and human-built structures are important resources for this imperiled species, especially in intensively managed agricultural landscapes. Since these environments are likely to increase across the globe, more research is needed to better understand how bat species interact with one another and the landscape to allow for their persistence in these extreme ecosystems.
Advisors: Craig. R. Allen and Dirac Twidwell