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Vocal Development in a Beluga Calf (Delphinapterus leucas)
Abstract: Acoustic communication is central to the socioecology of cetaceans. Knowledge of the ontogeny of their extensive repertoires is scant, and even less is known about the role of learning in vocal development. To examine these issues, the development of calls of one male beluga (Delphinapterus leucas) calf was systematically studied at the Vancouver Aquarium throughout his first year of life and opportunistically through his second and third years. He vocalized within the first hour after birth, producing exclusively low energy, broadband pulse trains. Both the dominant frequency and the pulse repetition rate of the pulsed calls increased with age. He acquired rudimentary whistles at 2 wks of age. During the second month, whistle production increased substantially. Whistle dominant frequency tended to increase with age, and at least in his first year, whistles did not attain full stereotypy. The calf started using mixed call types consistently at 4 mo. While some sounds tended to be more variable at later ages, his mixed calls progressively lost variability and increasingly resembled his mother’s most predominant stereotyped mixed call type. By 20 mo, this call type was fully stereotyped. Six months after he was exposed to his father’s sounds, he incorporated one of his father’s call types into his repertoire. These findings are discussed in light of current theories of sound production mechanisms in odontocetes, developmental stages of vocal acquisition, and vocal learning.
Key Words: repertoire development, acoustic communication, vocal learning, cetacean, ontogeny, beluga, Delphinapterus leucas
Document Type: Research article
Page Numbers: 123-143