Analysis of surface vocalizations from mother and pup Weddell seals (Leptonychotes weddellii)

Abstract

The antarctic Weddell seal (Leptonychotes weddellii) is a vociferous species with an extensive underwater repertoire, but little is documented about their airborne sounds. Weddell seals return to traditional pupping colonies, are approached easily, and recordings of individual seals are available from a tagging study conducted since the early 1970’s. Therefore, this study on airborne vocalizations of Weddell seal mothers and their pups provides a unique opportunity for detailed analysis of calls. During 1976, 1977, 1979, and 1996, surface vocalizations of mother and pup Weddell seals were recorded. Analysis variables included beginning, ending, maximum, and minimum frequency, fundamental harmonic interval, components per call, intercall interval, and duration. This study determined that surface calls of Weddell seal pups changed as the pup grew older. Although pups within an age bracket showed little variability in call structure, adult vocalizations varied among individuals. Relatedness of mothers and pups could not be concluded solely by the call variables examined. Further studies need to be conducted to determine the extent of the change that pup vocalizations undergo as they mature and to identify the acoustic variables influencing mother/pup vocalizations. [Acknowledgments: Dr. Jeanette Thomas, Dr. Douglas Quin, Bart Jones.]