Evolution of vocal control in echolocating bats

Echolocating bats display a large repertoire of behavioural plasticity, with vocal flexibility as a core constituent. The speed and accuracy of vocal adjustments executed by echolocating bats are unparalleled by other mammals, including humans. However, the evolutionary pressures behind the extraordinary vocal flexibility of echolocating bats remains elusive. Here we conducted a synthetic review to evaluate critically the probable drivers for all forms of vocal flexibility in echolocating bats. We show that many forms of bat echolocation flexibility, accounting for approximately 60% of vocal adjustment behaviours, function to mitigate acoustic interference, and thus can be attributed to auditory masking. Importantly, half of these anti-interference strategies are related to reafferent masking that is specific to active-sensing animals. We propose that auditory masking mitigation represents a strong selection pressure for the remarkable repertoire of vocal flexibility in echolocating bats.