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

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.

Diversity and Conservation of Cave-Dwelling Bats in the Brunca Region of Costa Rica

“…In Puerto Rico, for example, only 31% of the caves in the National Speleology database are used as roosts [49]. A similar study in Brazil shows that only about half of the observed caves had bats [50]. We also found that in combination, all caves harbor a total of 20 species.…”

Bat dynamics modelling as a tool for conservation management in subterranean environments

“…For example, our analysis confirmed this by the temperature range and the maximum temperature variables, which had the highest model contribution towards the mid-end hibernation period, limiting optimal habitat patches within hotter and more stable temperatures for thermophile bat species, such as Rhinolophus spp. Roost length was also relevant for bat abundance and species diversity in all of our studied subterranean environments, as Torquetti et al [19] also found, and was linked to larger patches of stable temperatures, therefore a wider selection of optimal habitats. At the beginning of the hibernation period most species and populations were corelated with smaller distances from the entrances, because they use the climatic variability to exit daily torpor and feed in optimal conditions [78], but during the colder winter…”

“…The maternity period usually requires proximity to the entrances, where temperatures are more suitable for nursing [19], except for the case of temperature inversions, where the colonies can be formed even in deep sectors of the roosts (SE 10), as our models also predicted. Often smaller sites with exterior hot air influxes are preferred [19].…”

“…Cave microclimatic conditions strongly influence bat populations [ 15 – 17 ] as they require optimal habitat patches within their roosts to ensure a successful hibernation or nursing cycle. The animals balance their energy reserves during the cold season [ 14 , 18 ], and search for hotter areas during the nursing season [ 19 ]. The stable temperature values recorded in deep sectors of SEs often reflect the exterior annual average temperatures [ 20 , 21 ].…”

Spatiotemporal analysis of rabies in cattle in central Mexico

“…In contrast, our study found a more than three times higher average (12.9 °C) suggesting good adaptation of the vampire bat to the climatic conditions in the study region. It is known that D. rotundus does not hibernate, but lives long periods in caves, in tree holes, under bridges and in old buildings during the day where the microclimate differs from that of the general environment (Torquetti et al, 2017). In fact, it has been reported that the factors that most contribute to the spatial distribution of rabies in livestock are temperature and precipitation as these variables offer a micro-climate inside bat refuges that favour the distribution of possible infected vampire bats with the rabies virus (Bárcenas-Reyes, 2013;Bárcenas-Reyes et al, 2015;de Thoisy et al, 2016;Hayes and Piaggio, 2018).…”