Abstract
Remote acoustic monitoring is a non-invasive tool that can be used to study the distribution, behavior, and habitat use of sound-producing species. The North Atlantic right whale (Eubalaena glacialis) is an endangered baleen whale species that produces a variety of stereotyped acoustic signals. One of these signals, the “gunshot” sound, has only been recorded from adult male North Atlantic right whales and is thought to function for reproduction, either as reproductive advertisement for females or as an agonistic signal toward other males. This study uses remote acoustic monitoring to analyze the presence of gunshots over a two-year period at two sites on the Scotian Shelf to determine if there is evidence that North Atlantic right whales may use these locations for breeding activities. Seasonal analyses at both locations indicate that gunshot sound production is highly seasonal, with an increase in the autumn. One site, Roseway West, had significantly more gunshot sounds overall and exhibited a clear diel trend in production of these signals at night. The other site, Emerald South, also showed a seasonal increase in gunshot production during the autumn, but did not show any significant diel trend. This difference in gunshot signal production at the two sites indicates variation either in the number or the behavior of whales at each location. The timing of the observed seasonal increase in gunshot sound production is consistent with the current understanding of the right whale breeding season, and our results demonstrate that detection of gunshots with remote acoustic monitoring can be a reliable way to track shifts in distribution and changes in acoustic behavior including possible mating activities.
Highlights
Understanding patterns of animal communication can reveal critical information about life history [1]
The production of loud acoustic signals for long-range communication provides an opportunity for using remote acoustic sensing to capture annual trends and seasonal changes in signal production of a variety of species [3,4,5,6,7,8]
Gunshots occurred in all months of the year at the Emerald location, while only occurring June through December at the Roseway West site
Summary
Understanding patterns of animal communication can reveal critical information about life history [1]. The production of loud acoustic signals for long-range communication provides an opportunity for using remote acoustic sensing to capture annual trends and seasonal changes in signal production of a variety of species [3,4,5,6,7,8]. Commonly referred to as passive acoustic monitoring (PAM), uses autonomous recorders to collect data for long periods of time with minimal disturbance to the environment. Such recording units allow researchers to collect acoustic data in remote locations or during weather conditions or seasons that would otherwise prohibit direct observation [9,10]
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