Fire, land cover, and temperature drivers of bat activity in winter

Marcelo H Jorge,Michael C True,Michael J Cherry,Katherine M Gorman,Sara E Sweeten,W Mark Ford,Samuel R Freeze,Elina P Garrison,Hila Taylor

doi:10.1186/s42408-021-00105-4

Abstract

BackgroundUnderstanding the effects of disturbance events, land cover, and weather on wildlife activity is fundamental to wildlife management. Currently, in North America, bats are of high conservation concern due to white-nose syndrome and wind-energy development impact, but the role of fire as a potential additional stressor has received less focus. Although limited, the vast majority of research on bats and fire in the southeastern United States has been conducted during the growing season, thereby creating data gaps for bats in the region relative to overwintering conditions, particularly for non-hibernating species. The longleaf pine (Pinus palustris Mill.) ecosystem is an archetypal fire-mediated ecosystem that has been the focus of landscape-level restoration in the Southeast. Although historically fires predominately occurred during the growing season in these systems, dormant-season fire is more widely utilized for easier application and control as a means of habitat management in the region. To assess the impacts of fire and environmental factors on bat activity on Camp Blanding Joint Training Center (CB) in northern Florida, USA, we deployed 34 acoustic detectors across CB and recorded data from 26 February to 3 April 2019, and from 10 December 2019 to 14 January 2020.ResultsWe identified eight bat species native to the region as present at CB. Bat activity was related to the proximity of mesic habitats as well as the presence of pine or deciduous forest types, depending on species morphology (i.e., body size, wing-loading, and echolocation call frequency). Activity for all bat species was influenced positively by either time since fire or mean fire return interval.ConclusionOverall, our results suggested that fire use provides a diverse landscape pattern at CB that maintains mesic, deciduous habitat within the larger pine forest matrix, thereby supporting the diverse bat community at CB during the dormant season and early spring.

Highlights

Understanding the effects of disturbance events, land cover, and weather on wildlife activity is fundamental to wildlife management
Statistical analysis To estimate the effects of fire and site environmental conditions on nightly bat species activity by detector site during the dormant season, we modeled the effects of environmental factors on bat activity with Generalized Linear Mixed Models (GLMMs) using a negative binomial distribution with zero inflation with the GLMMAMDB package (Skaug et al 2006) using R programming language
We found that overall bat activity rates differed across land cover, fire, and survey period, with land cover and fire differences likely explained by bat body size

Summary

Introduction

Understanding the effects of disturbance events, land cover, and weather on wildlife activity is fundamental to wildlife management. Most research suggests that reductions in forest clutter following burning tend to increase bat foraging activity relative to unburned conditions (Ford et al 2006; Loeb and Waldrop 2008; Cox et al 2016; Silvis et al 2016; Austin et al 2018b). This is true for larger-bodied, less maneuverable bats with lower echolocation call frequencies (Austin et al 2018a), but less so for smaller-bodied, more maneuverable bats with higher echolocation call frequencies (Starbuck et al 2020). Considerable data gaps exist for both migratory and non-hibernating resident bat species in the portions of the Southeast where these species overwinter and are often active during vegetative dormant season (Carter et al 2002)

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