Effects of fire and its severity on occupancy of bats in mixed pine-oak forests

Abstract

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.

 

Keywords

Bats, prescribed fire, occupancy, vegetation structure, forest management, fire severity

Citation

Burns, Leanne K.L.; Loeb, Susan C.; Bridges, William C. 2019. Effects of fire and its severity on occupancy of bats in mixed pine-oak forests. Forest Ecology and Management. 446: 151-163. https://doi.org/10.1016/j.foreco.2019.05.024.