Multimodal shifts in noise: switching channels to communicate through rapid environmental change

Abstract

A multimodal shift is the ability to switch from reliance on one sensory channel to another during communication. The shift can take place during signal production and/or perception. If environmental changes such as urbanization and climate change impair signal transmission in particular channels, it would benefit the animal to be able to switch to a relatively quieter channel. For this strategy to be successful, it requires animals to be able to send redundant information across multiple channels. I develop and explore the argument that the ability of animals to switch from a noisy channel to a relatively quiet one may be key for the animals' ability to cope with rapid anthropogenic environmental change. I review examples of multimodal shifts that occur with environmental noise as well as cases in which a predicted shift did not occur. I survey which sensory channels are used in shifts and whether the signal components are redundant or nonredundant. Most multimodal shift examples include the visual channel as one of the components. The majority of signals involved in shifts appear to be redundant, although the majority of signals involved in multimodal communication in general appear to be nonredundant, especially for chemical/visual combinations. Finally, I discuss how anthropogenic environmental changes can affect signal transmission in different channels and habitats and explain why the ability to shift channels may help animals cope with these changes. Predictions and recommendations for future work are provided.