Bat Activity at Woodland/Farmland Interfaces in Central Delaware

Bats vary their activity with different features of habitat, resource availability, predation risk, and other factors. Agricultural fields may provide an abundance of insect prey, but are also risky habitats due to their exposure. How bats use mixed landscapes is important information for biologists, as increasing development affects the amount of suitable habitat and impacts bat populations in the region. Using acoustic recording, we monitored relative bat activity in open areas and edges of the woodland/farmland interface of agricultural fields in Kent County, DE. We examined bat activity among different sites, in openings versus edges, among crop types, relative to nearby forest fragment size and shape, and under different weather conditions. Bat activity was significantly higher along edges than in the open in the agricultural fields for passes/night, but we found no differences among crop types or sites and no interaction effects. We also found no effect of size or amount of edge of a fragment on bat activity. We found significant negative correlations between passes and temperature and wind speed, and significant positive correlations between passes and relative humidity and barometric pressure. Bats use agricultural areas for foraging, and the woodland interfaces along these fields are important for bat activity. This study provides data that may help engender conservation practices, such as retention of forested edges and maintenance of tree lines, and perhaps crop selection and pest control management, in the region's farming community.