Energy constraints and strategies in flying and swimming animals

Animal movement requires energy. The cost of movement includes the locomotion required to move through space as well as the metabolic cost of maintaining homeostasis during movement. Thus, there is a trade-off between the costs of locomotion and metabolism, given that the latter increases proportionately with movement duration. In the case of ectothermic animals, the thermal environment affects an individual’s metabolic activity, and thus limits its use of space within a temperature range. Recent developments in the fields of bio-logging and biomechanics have allowed us to understand how movement costs are reduced in animals via morphology and movement pattern. For example, hydrodynamic body shapes and cost-efficient movement strategies greatly reduce locomotive costs in aquatic environments. The trade-off in costs over the duration of a given movement can be used to predict theoretically the optimal movement strategy of an animal; in many cases, these predictions are validated by behavioural observations in the field. This approach may be effective for understanding the morphological and behavioural diversity of many animal taxa and predicting their fate in changing environments.