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Naturwissenschaften

, 94:49 | Cite as

Parent–offspring communication in the Nile crocodile Crocodylus niloticus: do newborns’ calls show an individual signature?

  • Amélie L. Vergne
  • Alexis Avril
  • Samuel Martin
  • Nicolas Mathevon
Short Communication

Abstract

Young Nile crocodiles Crocodylus niloticus start to produce calls inside the egg and carry on emitting sounds after hatching. These vocalizations elicit maternal care and influence the behaviour of other juveniles. In order to investigate the acoustic structure of these calls, focusing on a possible individual signature, we have performed acoustic analyses on 400 calls from ten young crocodiles during the first 4 days after hatching. Calls have a complex acoustic structure and are strongly frequency modulated. We assessed the differences between the calls of the individuals. We found a weak individual signature. An individual call-based recognition of young by the mother is thus unlikely. In other respects, the call acoustic structure changes from the first to the fourth day after hatching: fundamental frequency progressively decreases. These modifications might provide important information to the mother about her offspring—age and size—allowing her to customize her protective care to best suit the needs of each individual.

Keywords

Parent–offspring communication Acoustic communication Nile crocodile Newborns’ calls 

Notes

Acknowledgments

We warmly thank Luc Fougeirol and Clémentine Vignal for their support and advice, Erik Zornik for English improvement, as well as two anonymous referees and Dr. Czeschlik for their useful comments. This study was funded by ‘La Ferme aux Crocodiles’ and by a grant of the Institut universitaire de France (IUF) to N.M. This work complies with the current laws of France.

Supplementary material

114_2006_156_MOESM1_ESM.wav (38 kb)
S1 Call emitted by crocodile a on the first day after hatching (soundfile: S1.wav) (WAV 39 kb)
114_2006_156_MOESM2_ESM.wav (48 kb)
S2 Call emitted by crocodile b on the first day after hatching (soundfile: S2.wav) (WAV 49 kb)
114_2006_156_MOESM3_ESM.wav (45 kb)
S3 Call emitted by crocodile c on the first day after hatching (soundfile: S3.wav) (WAV 46 kb)
114_2006_156_MOESM4_ESM.wav (41 kb)
S4 Call emitted by crocodile a on the second day after hatching (soundfile: S4.wav) (WAV 42 kb)
114_2006_156_MOESM5_ESM.wav (36 kb)
S5 Call emitted by crocodile a on the third day after hatching (soundfile: S5.wav) (WAV 37 kb)

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Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • Amélie L. Vergne
    • 1
    • 2
  • Alexis Avril
    • 1
    • 2
  • Samuel Martin
    • 3
  • Nicolas Mathevon
    • 1
    • 2
  1. 1.ENES EA3988, Université Jean MonnetSaint-Etienne cedex 2France
  2. 2.‘The BioAcoustics Team’Université Paris XI NAMC CNRS UMR8620Orsay cedexFrance
  3. 3.La Ferme aux CrocodilesPierrelatteFrance

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