Hibernation is a physiological and behavioral adaptation that allows many species of small mammals to survive periods of seasonal scarcity in energy or water. Hibernation research has historically been pursued largely by physiologists and, until recently, few studies have examined how ecological and behavioral factors affect the expression of hibernation in the wild. Herein, I detail the results of five studies on the ecology, physiology, and behavior of cavernicolous bats in nature. First, I update decades old survival estimates of an endangered species, the Indiana bat (Myotis sodalis) using modern demographic analyses. Second, I show that unlike commonly assumed in the literature, hibernating bats do not all prefer hibernating at the coldest temperature possible, and instead choose microclimates for hibernation in accordance with the predictions of an optimization framework. Third, I show that the benefit of a common thermoregulatory behavior, clustering during hibernation, is likely a byproduct of the need to save energy during energetically expensive euthermic arousals. Fourth, I create an individual-based model (IBM) to estimate survival rates of hibernating bats under situations that are impossible or unethical to test experimentally and show that winter length has little effect on survival and that the paradigm that all disturbances are detrimental to bats is likely unwarranted. Finally, I use the same IBM to test several hypotheses explaining the starvation of bats affected by White-Nose Syndrome (WNS), a disease which is decimating populations of hibernation bats. I then extend the model to determine the efficacy of a possible intervention—the inclusion of warm "thermal refugia" in the caves—in slowing mortality associated with WNS.