Road and Habitat Interact to Influence Selection and Avoidance Behavior of Bats in Indiana

Research on the ecology of bats and roads has largely covered impacts of major highways, but varying types of roads and surrounding habitats may differ in their impacts on bat activity. We conducted 28 mobile acoustic surveys in and around Indiana state forests from May to August 2012. We employed Manly's selection ratios to examine levels of bat activity along different types of roads through various habitats, and the interaction of road and habitat, using an exact chi-squared test. Activity was higher than expected along unpaved local roads and roads that were lined with open-canopy forest and forest edges, whereas activity was lower than expected along state highways and “other” roads (e.g., service roads), as well as roads within open areas. The influence of a road on activity was dependent on surrounding habitat features. For example, activity on unpaved local roads was greater than expected when surrounded by closed-canopy forest, but lower than expected when surrounded by human development. Inventory and monitoring programs might be improved if they consider the interacting roles of road and habitat type in influencing how bats select their environment.