Grant: Discovery Grants Program - Individual

The proximate currency that best explains the behaviour by animals in general and endotherms in particular, is energy. Research has focused on energy acquisition whereas my ongoing focus is to determine how, when and why endotherms (birds and mammals) employ heterothermy (e.g., torpor). For endotherms, defending a constant elevated body temperature confers fundamental physiological advantages. However the benefits must be balanced against high energetic costs, which come with elevated metabolic rates. These high costs can be offset by periods of torpor which results in reduced metabolic rates and as a consequence energetic savings. To enhance the general applicability of our research, my students and I work on insectivorous bats and nocturnal insect eating birds (nightjars). Despite the phylogenetic distance between them, these groups converge ecologically and physiologically. My short-term goal is to identify patterns in approaches to heterothermy in birds and mammals by addressing questions about why some groups of endotherms employ torpor, why certain individuals employ it when they do, what the cues are that initiate the physiological response and why there is flexibility between individuals in their propensity to employ this strategy. Over the next five years, my students and I will assess the importance of factors including inclement weather, food scarcity for reasons other than cold (e.g., seasonal drought), reproductive status, and day roost structure, on the use of torpor and overall energetics of caprimulgid birds and vespertilionid bats. The cosmopolitan distribution of these groups and their variable habitat requirements, coupled with basic similarities in foraging strategies despite differences in sensory capabilities, make them good model taxa to elucidate the general influence of these factors on endotherms.