Habitat-associated and temporal patterns of bat activity in a diverse forest landscape of southern New England, USA

The development and use of acoustic recording technology, surveys have revealed the composition, relative levels of activity, and preliminary habitat use of bat communities of various forest locations. However, detailed examinations of acoustic surveys results to investigate temporal patterns of bat activity are rare. Initial active acoustic surveys of bat activity on the Quabbin Reservoir watershed in central Massachusetts recorded high numbers of call sequences by five bat species. The results showed the importance of aquatic and open habitats for bats in this diverse forest landscape. Because the preliminary surveys were restricted in extent (habitats), number (replicates), and duration (active surveys only, limited number of repeated surveys), the authors strongly recommended more comprehensive and extensive surveys of bat activity on the area. This paper reports the results of active (manual) and passive (automated) acoustic bat activity surveys in three replicates of ten habitats, conducted three to four times per year over the course of the study between 2004 and 2006. Over the full study, 2,800 actively-recorded 37,632 passively-recorded call sequences were examined and identified to species when possible. General patterns in activity did not differ by habitat between the two survey methods. Call sequences were recorded more often in open, especially aquatic habitats than in cluttered habitats. The use of passive surveys allowed for the assessment of temporal patterns of activity and an analysis of the relationship between ambient temperature and activity.