Animal Cognition

, Volume 13, Issue 3, pp 471–482 | Cite as

Mother–Calf vocal communication in Atlantic walrus: a first field experimental study

  • Isabelle Charrier
  • Thierry Aubin
  • Nicolas Mathevon
Original Paper

Abstract

In all colonial pinnipeds studied, mother–young vocal recognition exists and allows rapid and reliable meetings in spite of the confusing environment of the breeding colony. The efficiency of this recognition process guarantees pup survival, especially in species where females alternate foraging sea trips and lactation periods on land. The Atlantic Walrus (Odobenus rosmarus rosmarus) is a highly gregarious pinniped with females attending their calves for an extended period of time (2–3 years). Although we expect mother–calf vocal recognition to occur in this species due to the high density of individuals packed in herds, it has never been experimentally demonstrated. Here, we assessed the individual stereotypy of both mother and calf barks recorded in the wild by measuring frequency and temporal acoustic parameters. Both discriminant function and artificial neural network analyses resulted in high correct classification rates, underlying a well-defined individual stereotypy in parameters related to frequency modulation and frequency values. Playback experiments showed that mothers were more responsive to the barks of their own calf than to those of unrelated young. Finally, propagation experiments revealed that barks propagate at greater distances over water surface than over ice, acoustic features such as frequency modulation and frequency spectrum being highly resistant to degradation during propagation. Thus, acoustic analysis and propagation experiments suggest that these frequency parameters might be the key acoustic features involved in the individual identification process. This experimental study clearly demonstrates that Atlantic walrus has developed a highly reliable mother–calf vocal communication allowing such strong social bond.

Keywords

Vocal communication Mother–young interaction Maternal care Individual recognition Signature Pinnipeds 

Notes

Acknowledgments

This research has been funded by the French Polar Institute (IPEV, France—IC: program Arctic 450) and by the CNRS (French Institute for Scientific Research). NM is funded by the Institut Universitaire de France. The study was approved by the Ethical Committee of the French Polar Institute in France and by the Freshwater Institute Animal Care Committee (Animal Care Protocol: FWI-ACC-2005-2006-003; DFO Research License: S-08-09-1001-NU) in Canada. We would like to thank Tamaressee Akittirq and Brad Parker for providing us a great help in organising this fieldwork, and all the logistics in Igloolik. We also warmly thank Pakak Qamaniq, Laimikie Iqqaqsaq, Sam Iqqaqsaq our local guides for their wonderful help to find walruses. Special thanks to HTA Igloolik members and Qikiqtaaluk Wildlife Board Members for approving our research program. We also thank Vincent Rouvreau for his invaluable assistance with ANN methods; Ian Stirling, Becky Sjare and Robert Stewart for their assistance and their helpful advice in developing this project in the Canadian Arctic; Andrew Iwaniuk and Ben Pitcher for their useful comments on an earlier draft of the manuscript; and reviewers for their constructive comments. Special thanks to Antonio Fischetti for his great audio and video documentaries, and his gigantic patience during the 2008 fieldtrip.

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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Isabelle Charrier
    • 1
    • 2
  • Thierry Aubin
    • 1
    • 2
  • Nicolas Mathevon
    • 1
    • 3
  1. 1.CNRS, NAMCOrsayFrance
  2. 2.Université Paris SudOrsayFrance
  3. 3.Sensory Ecology and Neuro-Ethology LabUniversité Jean MonnetSaint-EtienneFrance

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