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The “landscape of heat”: behavioural thermoregulation and its impact in a warming world.

The “landscape of heat”: behavioural thermoregulation and its impact in a warming world.

Dr. Susan Cunningham
FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, University of Cape Town, South Africa

Climate change poses an ever-increasing threat to all organisms – perhaps especially those living in places that are already hot. For endotherms like birds, maintaining body temperature within safe bounds is fundamentally important for performance and survival. Endotherms can maintain safe body temperatures in the face of increasing environmental temperatures by adjusting aspects of physiology (e.g. evaporative water loss rates) and behaviour (e.g. ceasing activity and seeking shade). Behavioural modifications like shade-seeking can be an important buffer against physiological impacts of high temperatures, reducing costs of hyperthermia and dehydration and extending survival times under extreme conditions. However, behavioral adjustments can impose significant costs of their own in the form of missed opportunities that can affect individual body condition, the outcomes of breeding attempts, and potentially intra- and interspecific interactions. Using examples from our avian study systems in the Kalahari Desert of southern Africa, I will outline the behavioral trade-offs birds face in navigating thermal landscapes, the associated missed-opportunity costs, and consequences for proxies of fitness. We argue that the consequences of these behavioural trade-offs are likely to be profound, potentially impacting not only individual fitness and population persistence, but also the way species interact with others, with potential for cascading ecological effects. We speculate that these effects of the “landscape of heat” could be as important as the those of the “landscape of fear” in shaping community and ecosystem function under ongoing climate change. In order to understand whether and how arid systems might continue to function in an ever-warmer world, we must begin to integrate the overlooked consequences of behavioural thermoregulation into our frameworks for predicting climate change impacts on individuals, populations, species and ecosystems.