Across the diurnal cycle, all animals, birds and fish make frequent behavioural decisions (e.g. to forage or rest) which are influenced by the current environment (e.g. food availability and predation risk) and by the individual’s own internal states (e.g. energy reserves). I will talk about using stochastic dynamic programming as an approach to combine ecology and physiology to evaluate optimal decisions in animals across seasons, latitudes and climate change projections. My focus is on heterotherms using thermoregulation strategies such as torpor and hibernation, but this cost-benefit approach can be used in any system where individuals consider both physiological requirements and environmental conditions in their decision-making. If you consider your own study species – what are the internal states that can affect a decision between foraging or resting? Or between allocating resources into reproducing or growing? What are the environmental conditions that could influence the same choice?

