Variation in echolocation call emission of Neotropical insect-eating bats in response to shifting ambient temperatures.

The sensory systems of animals are essential for them to respond to environmental cues and signals. However, their functionality might be altered by climate change. Most bats, for example, rely on acoustic signal emission to acquire food, but their high-frequency echolocation calls are strongly attenuated in the air. Attenuation in air changes with changing weather conditions, which can lead to shifts in echo-based prey detection distance. However, bats can adjust call parameters to the task and environment, and this behavioural plasticity may help them to counteract potential increases in sound attenuation to keep echo detectability constant. We explored this ability in a community of insectivorous bats in a montane forest of Costa Rica. We recorded bat echolocation calls in response to experimentally increased temperatures, simulating intermediate and arguably realistic projected climate change scenarios. We calculated atmospheric attenuation and detection distance for each temperature and echolocation call. We found some changes in source level and call duration, yet not in peak frequency, and responses to increasing atmospheric attenuation were not consistent across species. This might be explained by several non-mutually exclusive reasons, including that the experimental increase in temperature and change of atmospheric attenuation were not sufficient to affect close-range prey detection. Ultimately, this study contributes to our understanding of sensory system adaptation under the pressure imposed by climate change.