Sound production and behavior in an eastern North Pacific killer whale population: Implications for autonomous remote monitoring.

Abstract

Remote acoustic monitoring is often used to determine the seasonal and spatial distributions of vocal animals, particularly when conditions of other monitoring approaches are limited. Additionally, sound production patterns might be used to infer important activities of free-ranging animals in the absence of other cues. Animals produce sounds during activities such as foraging and breeding, but such patterns are expected to vary between species/populations that are based on a variety of ecological factors. For example, fish-eating killer whales are more vocally active than mammal-eating killer whales, presumably since mammalian prey are sensitive to killer whale sounds. Southern Resident killer whales (SRKWs) are a fish-eating population found in coastal waters of Washington State and British Columbia. The goal of this study was to extend previous work on the behavioral correlates of sound production in SRKWs. We collected behavioral and acoustic data simultaneously over two field seasons and found that click occurrence as well as calling rates (calls/whale/min) were significantly higher when whales were foraging compared to traveling. Such patterns are useful for inferring events from remote acoustic monitoring. These results also indicate that communicative signals are particularly important during foraging activities in this population and have implications for noise disturbance.