Abstract
Adult Weddell seals (Leptonychotes weddellii) exhibit site fidelity to where they first breed but juveniles, and perhaps transient adult males, may disperse from their natal location. If there is mixing between adjacent breeding groups, we would expect that common vocalizations would exhibit clinal patterns. Underwater Trill vocalizations of male Weddell seals at Mawson, Davis, Casey, McMurdo Sound, Neumayer and Drescher Inlet separated by ca. 500 to >9,000 km, were examined for evidence of clinal variation. Trills are only emitted by males and have a known territorial defense function. Trills from Davis and Mawson, ca. 630 km apart, were distinct from each other and exhibited the greatest number of unique frequency contour patterns. The acoustic features (duration, waveform, frequency contour) of Trills from Neumayer and Drescher Inlet, ca. 500 km apart, were more distinct from each other than they were from the other four locations. General Discriminant Analysis and Classification Tree Analysis correctly classified 65.8 and 76.9% of the Trills to the correct location. The classification errors assigned more locations to sites >630 km away than to nearest neighbours. Weddell seal Trills exhibit geographic variation but there is no evidence of a clinal pattern. This suggests that males remain close to single breeding areas throughout their lifetime.
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Acknowledgments
The field research was funded by the Australian Antarctic Division, National Science Foundation of the United States and Alfred Wegener Institute for Polar and Marine Research, Germany. Additional support was provided by the Natural Sciences and Engineering Research Council of Canada, the National Geographic Society, dqmedia and the Biodaqua student exchange program. The recordings were made by the authors, B. Pahl, D. Simon, P. Abgrall, P. Rouget, C. Kreiß, and H. Klinck and all were assisted by numerous expeditioners at the bases near which the recordings were made. K. Collins, L. Charlton, M. Rossong, I. Charrier and a reviewer for this journal provided advice on an earlier draft of this manuscript.
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Terhune, J.M., Quin, D., Dell’Apa, A. et al. Geographic variations in underwater male Weddell seal Trills suggest breeding area fidelity. Polar Biol 31, 671–680 (2008). https://doi.org/10.1007/s00300-008-0405-4
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DOI: https://doi.org/10.1007/s00300-008-0405-4