Bats and Caves: Activity and Ecology of Bats Wintering in Caves

Abstract

Temperate regions of the world undergo a marked range of seasonal variation, most becoming extremely cold during the winter. Bats are the only group of vertebrates that have successfully exploited caves as permanent shelter. Although bats may use caves throughout all year, their most important role in ecology of temperate bats is as hibernacula. Here, we summarize various aspects of bat hibernation ecology, including variation in flight activity at the cave entrance; patterns of bat hibernation behaviour; site selection in hibernacula, including the importance of temperature during hibernation; and level of bat movement activity inside the cave. In addition, we review present knowledge on white-nose syndrome, one of the most important threats to cave-dwelling bats.

Hibernation temperature-dependentPseudogymnoascus destructansinfection intensity in Palearctic bats

“…Wild bats do not maintain universally an optimum temperature for hibernation during the whole winter [33]. However, body surface temperature data collected from M. myotis showed that bats in a hibernaculum chose relatively stable temperatures to roost at throughout winter [47], demonstrating that a single body surface temperature taken at the end of hibernation is a reasonable proxy for the temperature that bats had been hibernating at during winter. The stability of the body surface temperature facilitated us to model the infection intensity as expressed by the fungal load and the number of UV fluorescent skin lesions relative to body surface temperatures measured at the end of hibernation.…”

“…A single body surface temperature measurement as a useful proxy for winter hibernation Temperature of a bat in torpor is determined by the ambient temperature at the roost and bat thermoregulation [46,47]. The ambient temperature in underground hibernacula changes with geomorphology of the cave or mine system, its water and air flow regime and weather conditions at the site, with the greatest variation at entrances.…”

“…First, we tested whether our single measurement taken during hibernation can be used as a proxy for seasonal hibernating temperatures. We used data published in Zukal, Berková [47] that report body surface temperatures measured biweekly between December 2002 and May 2003 in Moravian Karst, Czech Republic with a laser thermometer. To investigate seasonal stability of T, we excluded global outliers T o , satisfying condition…”

“…Following exclusion of 20 outliers from the previously published dataset measuring seasonal changes [47], body surface temperature of hibernating bats remained statistically stable in the Moravian Karst (Czech Republic) between 13 December, 2002 and 2 May, 2003 (mean = 2.91°C, SD = 0.78, n = 216, linear model: α 0 ¼ 2:99; α 1 ¼ À 0:0012; F 1;214 ¼ 0:66; p ¼ 0:42). This result shows that bats choose relatively stable roosts during winter and that a single body surface temperature measurement of a hibernating bat is a suitable approximation of the temperatures experienced throughout winter hibernation.…”

Bat population recoveries give insight into clustering strategies during hibernation

“…As a result, individuals enter hibernacula over a period of several weeks, when their numbers on site fluctuate markedly and individual torpor bouts are short [5][6][7]. Towards the end of hibernation, a similar activity occurs, bats change roosts in hibernacula more frequently, move closer to the entrance of underground spaces, and might emerge on warm nights [8,9]. The direction of draught at the hibernaculum entrance can signal current weather conditions and thus affect torpor bouts or emergence from hibernation in spring [10].…”