Ecological influences on the use of torpor by Caprimulgid birds and Vespertilionid bats

点击翻译按钮获取中文摘要

Energy is the currency by which the costs and benefits of many biological functions are measured and likely best explains behaviour by animals in general and endotherms in particular. My research program is focused on determining the ecological context for how, when and why endotherms use torpor to save energy. Torpor stems from reduced metabolism and thus reduced body temperature (Tb) leading to energetic savings. Its importance is underscored by the rapidly increasing number of species recorded to use it and the idea that it makes endotherms less susceptible to extinction. We study the use of daily torpor by both insectivorous bats and nocturnal birds (nightjars) whose responses converge ecologically and physiologically. In the short-term we will identify broad patterns in torpor use with my long-term goal being to address why individuals employ it when they do, the cues used to initiate the physiological response and finally the reasons for the apparent flexibility of its use. Behavioural and ecological factors that likely influence torpor use include: body condition, social interactions, foraging success and roost structure. The relative importance of these factors is poorly understood and our research will assess the nature of interactions between them. We will measure torpor use by bats and birds in natural situations as part of both a long-term study of big brown bats in Cypress Hills, Saskatchewan and short-term studies of a variety of species including big brown, slit-faced and Egyptian fruit eating bats and Common Poorwills, Pauraques and Freckled Nightjars. In most projects, temperature sensitive radio-transmitters or data loggers will be used to collect data on how free living animals use torpor. Where possible, we will experimentally manipulate food availability and or the energetic costs incurred by study animals to assess which factors are most important for stimulating torpor use.