Exploring mechanisms underlying heterospecific alarm call responses in meerkats and yellow mongooses

"Eavesdropping" on heterospecific alarm calls is common, but we are only beginning to understand the cognitive mechanisms involved. A key question is whether eavesdropping results from innate perceptual sensitivities to acoustic features that are common to the calls of diverse species, or if it is a learned behavior. Here, we used playback experiments to investigate whether wild and captive meerkats (Suricata suricatta), and wild yellow mongooses (Cynictis penicillata) respond in a functionally appropriate way, ie successfully "eavesdrop", to heterospecific alarm calls. We tested calls from both sympatric and allopatric species to reveal whether responses were a result of learned associations between call types and their referents, or of innate perceptual sensitivities to their acoustic features. By playing back calls which signal either "aerial" or "general" predation threats, we also explored whether subjects could differentiate between the underlying function of heterospecific alarm calls. Our results show that wild meerkats and wild yellow mongooses, but not captive meerkats, were more likely to respond to the alarm calls of sympatric species. Additionally, wild, but not captive, meerkats were also more likely to flee as a response to aerial as opposed to general alarm calls. This indicates that learning likely affects the response of mongooses to heterospecific alarm calls. However, other factors are also likely to have an impact on how individuals in different populations of the same species respond to heterospecific alarm calls, such as innate perceptual sensitivities, external threats, the need to respond, and the soundscape a species is exposed to.