Behavioural thermoregulation compensates for changes in solar insolation in a wild insect

Knowledge of how animals use behaviour to adapt to changing environmental conditions is important for understanding how they will be impacted by climate change. Rising global temperatures are increasing the moisture-holding capacity of air, leading to greater cloud cover, which attenuates shortwave radiation, reducing the amount of radiation reaching animals on the ground. We experimentally investigated how changes in cloud cover may impact ectotherms that bask in sunshine to regulate their body temperature. We manipulated the degree of shade experienced by an annual insect, the field cricket, Gryllus campestris, under natural and seminatural conditions. Shading nymphs in large field boxes did not affect development time and had only a small negative effect on mass at maturity. To investigate whether crickets were able to compensate for increased shade through changes in their behaviour, we monitored the activity of experimentally shaded and unshaded wild cricket nymphs. Unshaded nymphs sought shade at midday, whereas shaded nymphs basked throughout the day in the most sunlit positions. Most ectotherms are profoundly affected by the energy they receive from sunlight. Our findings suggest that mobile ectotherms may be able to compensate for changes in cloud cover. However, they may incur costs due to greater exposure to threats such as predation. Understanding behavioural flexibility and the costs and benefits of different strategies is required to make accurate predictions about how terrestrial ecosystems will be impacted by changing solar insolation due to climate change.