Behaviour 2019
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Acoustic crypsis via habitat seleciton in Southern right whales
Julia M. Zeh, Julia R. G. Dombroski, Susan E. Parks. Syracuse University, Syracuse, New York, United States

Acoustically cryptic animals have adapted to reduce the detectability of their acoustic signals. Most studies of acoustic crypsis focus on signal properties, but we propose that habitat selection can also confer crypsis. For example, animals can avoid detection by choosing habitats with poor propagation. To test this hypothesis, we studied the acoustic propagation characteristics of Southern right whale calving habitats. Across populations, Southern right whale mother/calf pairs aggregate in shallow, sandy, nearshore waters. We modeled propagation of right whale calls in these environments using the Monterey Miami Parabolic Equation (MMPE). We also modeled the propagation of killer whale calls, since killer whales are the primary predator of Southern right whales. Across all three study sites, models indicate that calls from a nearshore right whale would only be detectable out to 500m, while a killer whale calling offshore would be detectable out to >5km. Thus, mother/calf pairs can remain acoustically cryptic while still listening for potential predators. Future studies of habitat selection should consider modeling the acoustic propagation characteristics of the environment.