Shaken, not stirred: blue whales show no acoustic response to earthquake events

<strong>Shaken, not stirred: blue whales show no acoustic response to earthquake events</strong> <br> Authors: Dawn R. Barlow¹*, Mateo Estrada Jorge^1,2, Holger Klinck^3,4, Leigh G. Torres¹ <br> ¹Geospatial Ecology of Marine Megafauna Lab, Marine Mammal Institute, and Department of Fisheries and Wildlife, Oregon State University, Newport, Oregon, USA ²Department of Computer Science and Department of Physics, Oregon State University, Corvallis, Oregon, USA ³K. Lisa Yang Center for Conservation Bioacoustics, Cornell University, Ithaca, New York, USA ⁴Marine Mammal Institute, Department of Fisheries, Wildlife and Conservation Sciences, Oregon State University, Newport, Oregon, USA <br> *[e-mail] <br> <strong>Abstract: </strong>Quantifying how animals respond to disturbance events bears relevance for understanding consequences to population health. We investigate whether blue whales respond acoustically to naturally occurring episodic noise by examining calling before and after earthquakes (27,040 calls, 32 earthquakes; 27 January-29 June 2016). Two vocalization types were evaluated: song and D calls. Blue whales did not alter the number of D calls, D call received level, or song intensity following earthquakes (paired t-tests, p&gt;0.7 for all). Linear models accounting for earthquake strength and proximity revealed significant relationships between change in calling activity surrounding earthquakes and prior calling activity (D calls: R²=0.277, p&lt;0.0001; song: R²=0.080, p=0.028), however this same relationship was true for “null” periods without earthquakes (D calls: R²=0.262, p&lt;0.0001; song: R²=0.149, p=0.0002), indicating that the pattern is driven by blue whale calling context regardless of earthquake presence. Our findings that blue whales do not respond to episodic natural noise provides context for interpreting documented acoustic responses to anthropogenic noise sources, including shipping traffic and petroleum development, indicating that they potentially evolved tolerance for natural noise sources but not novel noise from anthropogenic origins.