Bat activity during autumn relates to atmospheric conditions: implications for coastal wind energy development


The cryptic behavior of migrating bats leaves us largely uninformed of their seasonal distribution and abundance, important movement corridors, and migration behaviors. However, models of avian migration in relation to meteorological variables may prove useful in describing seasonal patterns of coastal bat activity. We pursued 2 primary objectives regarding regional autumn bat activity along the Atlantic Coast of southern New England, United States, inferred from continuous acoustic monitoring: 1) to evaluate hypotheses regarding the association of regional atmospheric conditions and coastal bat activity and 2) to construct and evaluate models that predict regional bat activity on a given night using meteorological data accessed ahead of the activity. Acoustic bat activity was attributable primarily to 2 species of migratory tree bats, red bat and silver-haired bat, but also the short-distance migrant tricolored bat and generally sedentary big brown bat. Myotis spp. and hoary bat detections were relatively uncommon among classified calls. Coastal bat activity varied with regional wind conditions indicative of cold front passage and expected to induce a more coastal flight path, but associations with other atmospheric conditions from models of songbird migration were typically weak. Bat acoustic activity also was associated strongly with various aspects of temperature. Predictive models of regional nightly bat activity were reasonably accurate in anticipating nights of the highest and lowest bat activity, particularly for low-frequency bats such as silver-haired and big brown bat. The ability to anticipate high bat activity may help reduce adverse interactions with forthcoming wind energy development in coastal and offshore areas along the western Atlantic Ocean.

Journal of Mammalogy 97:1565-1577