Behavioral and environmental context of Antarctic minke whale vocalizations

Abstract

Acoustic signaling is the predominant form of communication between cetaceans, and understanding the behavioral state of calling individuals can provide insights into their function. We used multi-sensor tags equipped with concurrent video and acoustic recorders to characterize the vocal repertoire and associated behavior of Antarctic minke whales around the Antarctic Peninsula. Whale vocalizations were sorted into distinct call types based on several known acoustic parameters including 90% call duration, frequency bandwidth, and frequency quartiles. Call types were then compared to concurrent video and sensor data to determine the behavioral state and environmental conditions surrounding vocalizing individuals. We found several distinct sound types ranging in frequency from 180–560 Hz, consisting of pulse trains, down-sweeps, growls, and other sound types not previously described. These sounds are produced during distinct behavioral states including foraging, traveling, socializing, and resting and are emitted both in solitary and in groups of up to five animals. Additionally, vocalizations were emitted in both open water and sea ice conditions. By combining acoustic recordings with animal-borne video, our results represent a significant advancement in our understanding of Antarctic minke whale behavior and improve our capacity to acoustically monitor this species in a rapidly changing Antarctic region.