Budgeting heat and energy: How do birds do it?

I am fascinated by animals that can get cold to save energy. I study how animals allocate their daily energy budgets across various activities, and across environmental gradients. One component of regulating this daily energy budget is the ability to use heterothermy- lowering their body temperatures to save energy. Hibernation, for example, is a form of heterothermy. Birds like hummingbirds can use a daily version, called daily torpor, dropping their body temperature down as cold as 3°C. I have been studying torpor in hummingbirds, integrating ecological data, whole animal energetics, gene expression, and mitochondrial parameters to understand heterothermy across biological scales. At TIFRH, I am starting to integrate ecology, physiology, evolutionary perspectives, and molecular and imaging techniques to understand how heterothermic animals exist, with a focus on the Indian tropics.