Exploring the vocal ontogeny of North Atlantic right whales

The vocal ontogeny of species can provide insight into their physical and social development and capacity for social learning. North Atlantic right whales (Eubalaena glacialis) are an endangered species with a complex range of vocalizations used in a wide range of social contexts. In this study, we systematically characterize developmental changes in sound production from birth through adulthood. Calls have been recorded as part of ongoing North Atlantic right whale research projects spanning 2001 through 2015, and include data from calves as young as 1 month of age. Data included recordings from single hydrophones, hydrophone arrays, and non-invasive digital acoustic recording tags. Only calls which could be confidently attributed to a specific whale of known age were used in the analysis. Developmental periods consisted of 0–3 months, 3–6 months, 6–12 months, and then discrete ages by year. Calls of both male and female calves were included in the analysis. Calls were also classified to age categories using discriminant function analysis (DFA) to determine whether a calf could be aged by its call. Analyses indicate a gradual maturation of sound production with increasing age of individuals.