Acoustic characterization and vocal behavior of North Atlantic right whale surface active groups

Abstract

Focal acoustic surveys were conducted to assess the vocal behavior of North Atlantic right whales in the shallow waters of the southeast critical habitat. Underwater vocalizations were archived using autonomous buoys in close proximity to surface active groups (SAGs) providing sound production data vital for regional passive acoustic monitoring and conservation. Classification trees were used to examine the distinguishing characteristics of calls and quantify their variability within the surface active groups vocal repertoire. Calling rates were higher than those reported in the Bay of Fundy, which may be a factor of habitat demographics. Sound production rate and call type usage were correlated with group cohesion, revealing a consistent call distribution pattern across SAGs of varying sizes and composition. The within-bout clustering probability of low and high frequency calls suggest that temporal affinities between vocalization classes may be indicators of shared social functions. The results demonstrate that concurrent temporal and spectral analysis is powerful for investigating and presenting the interrelationships of calls with social behavior and group composition.