The energetic impacts of climate change vary along climatic gradients in mammals

Extreme temperature fluctuations are becoming more frequent due to climate change, likely increasing the cost of living of endotherms through their impact on the energy and water budgets. Yet, we know little about the magnitude of these impacts and whether species from different climatic regions will differ in their response to cold and heat waves. We confronted mechanistic models with field metabolic rate data (FMR) of mammals to analyze the response of energy and water balance to temperature anomaly across climatic gradients. FMR increased in response to both positive and negative anomalies in colder regions, and this pattern was consistent across both observed and modelled FMR. By contrast, warm-living mammals displayed lower FMR during heat waves, a pattern that was not captured by the model, probably due to physiological and behavioral adaptations to prevent water loss in warm, dry environments. The energetic impacts of climate change will differ among mammals inhabiting different climates, and therefore, species-specific parameterization is required for future mechanistic models to predict these impacts.