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.
This is a preview of subscription content, log in via an institution to check access.
References
Aubin T (1994) Syntana: a software for the synthesis and analysis of animal sounds. Bioacoustics 6:80–81
Aubin T, Jouventin P (2002) How to identify vocally a kin in a crowd? The penguin model. Adv Stud Behav 31:243–277
Beecher MD (1989) Signaling systems for individual recognition: an information theory approach. Anim Behav 38:248–261
Bradbury JW, Vehrencamp SL (1998) Principles of Animal Communication. Sinauer Associates, Sunderland, Massachusetts
Britton A (2001) Review and classification of call types of juvenile crocodilians and factors affecting distress calls. In: Grigg GC, Seebacher F, Franklin CE (eds) Crocodilian biology and evolution. Surrey Beatty & Sons PTY Limited, Chipping Norton, pp 364–377
Campbell HW (1973) Observations on the acoustic behaviour of crocodilians. Zoologica 58:1–11
Charrier I, Jouventin P, Mathevon N, Aubin T (2001). Individual identity coding depends on call type in the South Polar skua Catharacta maccormicki. Polar Biol 24:378–382
Charrier I, Mathevon N, Jouventin P (2003) Vocal signature recognition of mothers by fur seal pups. Anim Behav 65:543–550
Cott HB (1971) Parental care in Crocodilia, with special reference to Crocodylus niloticus. Proc. 1st. working meeting of Crocodile Specialists, IUCN Publ 32:166–180
Halliday T (1983) Information and communication. In: Halliday TR, Slater PJB (eds) Animal behaviour, communication, vol 2. Blackwell Scientific, Oxford, pp 43–81
Herzog HA (1975) An observation of nest opening by an American alligator Alligator mississippiensis. Herpetologica 31:446–447
Herzog HA, Burghardt GM (1977) Vocalization in juvenile crocodilians. Z Tierpsychol 44:294–303
Hunt RH, Watanabe ME (1982) Observations on maternal behaviour of the American alligator, Alligator mississippiensis. J Herpet 16:235–239
Pimentel (1979) Morphometrics: the multivariate analysis of biological data. Kendall–Hall, Dubuque, Iowa
Pooley AC (1977) Nest opening response of the Nile crocodile, Crocodylus niloticus. J Zool 182:17–26
Staton MA (1978) “Distress calls” of crocodilians—whom do they benefit? Am Nat 112:327–332
Young BA (2003) Snake bioacoustics: toward a richer understanding of the behavioral ecology of snakes. Q Rev Biol 78:303–326
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.
Author information
Authors and Affiliations
Corresponding author
Electronic supplementary material
Below is the link to the electronic supplementary material.
S1
Call emitted by crocodile a on the first day after hatching (soundfile: S1.wav) (WAV 39 kb)
S2
Call emitted by crocodile b on the first day after hatching (soundfile: S2.wav) (WAV 49 kb)
S3
Call emitted by crocodile c on the first day after hatching (soundfile: S3.wav) (WAV 46 kb)
S4
Call emitted by crocodile a on the second day after hatching (soundfile: S4.wav) (WAV 42 kb)
S5
Call emitted by crocodile a on the third day after hatching (soundfile: S5.wav) (WAV 37 kb)
Rights and permissions
About this article
Cite this article
Vergne, A.L., Avril, A., Martin, S. et al. Parent–offspring communication in the Nile crocodile Crocodylus niloticus: do newborns’ calls show an individual signature?. Naturwissenschaften 94, 49–54 (2007). https://doi.org/10.1007/s00114-006-0156-4
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00114-006-0156-4