Effects of fire and its severity on occupancy of bats in mixed pine-oak forests
Prescribed burning has become more common for the management of eastern forests in North America, so understanding if and how foraging bats respond to structural changes generated by ﬁre is of increasing importance. Our objective was to investigate the eﬀects of post-ﬁre landscape conditions on the occurrence of foraging bats in mixed forests of the Cumberland Plateau physiographic region. We deployed Anabat II bat detectors in 164 paired burned and unburned forest sites for ≥2 nights from mid-May through August 2014 and 2015 to monitor bat foraging and commuting habitat use. We conducted vegetation surveys to quantify site- speciﬁc structural characteristics, which indicated that measures of structure were signiﬁcantly lower in burned sites than unburned sites. We used Program Presence to test a priori hypotheses of species-speciﬁc probability of detection and site occupancy related to weather, burn history (i.e., site burned within the past 10 years or unburned), and site and landscape characteristics. Bats were detected at 94% of burned sites and 83% of unburned sites. Probability of detection was aﬀected by weather conditions, vegetative structure, and burn history for most species. Occupancy for all species/species groups examined was positively associated with burning and generally associated with lower vegetative structure. Although burn severity did not aﬀect most species groups, occupancy of Myotis species and tri-colored bats (Perimyotis subﬂavus) was lower in sites that received moderate severity burns than in sites that received low severity burns. Therefore, while prescribed ﬁre may provide vegetative structure conducive to eﬃcient foraging for all bats of the Cumberland Plateau, our results demonstrate that retaining some unburned forests while creating mosaics of lower and higher severity burns across the landscape will result in favorable foraging conditions for all resident bat species.