Differences between caves with and without bats in a Brazilian karst habitat

Camila G Torquetti,Marcos Xavier Silva,Sonia Talamoni

doi:10.3897/zoologia.34.e13732

Abstract

ABSTRACT. Since bats shelter in roosts during their period of diurnal inactivity, the quality and availability of roosts are important aspects of their ecology. Karst areas have great potential for the availability of day roosts, since they form caves, which serve as bat shelters. Here we characterize the caves used by bats in a preserved karst area of Southeastern Brazil. Using logistic regression analysis we identified the cave characteristics that influence bat occupation. Sixty-six caves were characterized based on measurements of internal height and width, height and width of the entrance(s) of the cave, number of entrances, maximum horizontal development of cave, and internal temperature and humidity. In nineteen months we found 14 species in 32 caves. Most species were eventually recorded in multiple caves, with the exception of D. rotundus, G. soricina and A. planirostris, which were always found in the same caves. Desmodus rotundus showed maternity roost fidelity. We found no differences in microclimate between the caves that are occupied and those that are not. In other words, the microclimate of the caves studied herein can be characterized as stable over the years. The only predictor affecting the presence of bats in the study area was the cave’s maximum horizontal development: the caves that are occupied have greater horizontal development. Based on our results, we conclude that bats occupy many of the caves and that some species are more frequent in certain caves than in others, including some roosts that are used as maternity roosts. These findings indicate that these caves are important resources for the bats in the karst environment studied, and should be preserved.

Highlights

Diurnal roosts are vitally important to bats because they serve as sites for mating, shelter and rest, care of offspring, as well as for social interactions (Twente 1955, Kunz and Lumsden 2003, Otto et al 2016)
Our data show that almost half of the studied caves are used by bats and that most species recorded eventually occupy these caves. The exceptions to this were D. rotundus, G. soricina and A. planirostris, which occupied the same caves almost continuously throughout the study period, indicating that individuals of these species roost in more permanent sites
The microclimate among the caves studied can be characterized as consistent, and it is stable over the year. These results are not surprising, given that variation in climate and weather are not pronounced in the study area (Sá-Jr et al 2012), and are likely insufficient to lead to selective pressure for the occupancy of a particular type of cave

Summary

Introduction

Diurnal roosts are vitally important to bats because they serve as sites for mating, shelter and rest, care of offspring, as well as for social interactions (Twente 1955, Kunz and Lumsden 2003, Otto et al 2016). Studies on the use of roosts are not rare (Sedgeley and O’Donnell 1999, Ruczynski and Bogdanowicz 2005, O’Keefe et al 2009, Otto et al 2016). These studies have shown that roost use is primarily influenced by climate (Kunz and Pierson 1994). The type of diurnal roost has profound implications for energy economy and the reproductive success of bats (Arlettaz et al 2001, Papadotou et al 2008, Sedgeley 2001, Pretzlaff et al 2010, Otto et al 2016)

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