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. 2015 Oct 1;1:27.
doi: 10.1186/s40851-015-0028-x. eCollection 2015.

Individuality Embedded in the Isolation Calls of Captive Beluga Whales (Delphinapterus Leucas)

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Free PMC article

Individuality Embedded in the Isolation Calls of Captive Beluga Whales (Delphinapterus Leucas)

Yuka Mishima et al. Zoological Lett. .
Free PMC article

Abstract

Introduction: Species with fission-fusion social systems tend to exchange individualized contact calls to maintain group cohesion. Signature whistles by bottlenose dolphins are unique compared to the contact calls of other non-human animals in that they include identity information independent of voice cues. Further, dolphins copy the signatures of conspecifics and use them to label specific individuals. Increasing our knowledge of the contact calls of other cetaceans that have a fluid social structure may thus help us better understand the evolutionary and adaptive significance of all forms of individually distinctive calls. It was recently reported that one type of broadband pulsed sounds (PS1), rather than whistles, may function as individualized contact calls in captive belugas. The objective of this study was to assess the function and individual distinctiveness of PS1 calls in an isolation context. Recordings were made from five captive belugas, including both sexes and various ages.

Results: PS1 was the predominant call type (38 % in total) out of five broader sound categories. One sub-adult and three adults had individually distinctive and stereotyped pulse repetition pattern in PS1; one calf showed no clear stereotyped pulse repetition pattern. While visual inspection of the PS1 power spectra uncovered no apparent individual specificity, statistical analyses revealed that both temporal and spectral parameters had inter-individual differences and that there was greater inter-individual than intra-individual variability. Discriminant function analysis based on five temporal and spectral parameters classified PS1 calls into individuals with an overall correct classification rate of 80.5 %, and the most informative parameter was the average Inter-pulse interval, followed by peak frequency.

Conclusion: These results suggest that belugas use individually distinctive contact calls in an isolation context. If belugas encode signature information in PS1 calls, as seen in bottlenose dolphins, the pulse repetition pattern may be the carrier, as it is individually stereotyped and appears to require vocal development. This idea is supported by the finding that the average inter-pulse interval is the most powerful discriminator in discriminant analysis. Playback experiments will elucidate which parameters are perceived as individual characteristics, and whether one of the parameters functions as a signature.

Figures

Fig. 1
Fig. 1
Schematic view of the beluga pool in the Port of Nagoya Public Aquarium, Japan. Each of the belugas was isolated in the medical pool
Fig. 2
Fig. 2
Examples of categorized call types: a PS1, b C1, c S, d W, and e O. The vertical and horizontal scales vary among call types
Fig. 3
Fig. 3
Frequency of each call type per session
Fig. 4
Fig. 4
Examples of PS1 calls from five belugas. The upper figures show waveforms, and the lower figures show spectrograms. Individual identities are represented at the upper left in the spectrograms
Fig. 5
Fig. 5
IPI contours of PS1 calls from five belugas (n = 16). Individual identities are represented at the upper left. Sixteen samples each from T, G, N, and M were randomly selected to match the number of depicted IPI contours of H from which the smallest samples were collected
Fig. 6
Fig. 6
Power spectra of PS1 calls from five belugas (n = 16). Individual identities are represented at the lower left. The power spectra were calculated from the middle pulse location within PS1 calls. Sixteen samples each from T, G, N, and M were randomly selected to agree with the number of depicted IPI contours of H from which the smallest samples were collected

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References

    1. Kondo N, Watanabe S. Contact calls: information and social function. Jpn Psychol Res. 2009;51:197–208. doi: 10.1111/j.1468-5884.2009.00399.x. - DOI
    1. Cortopassi KA, Bradbury JW. Contact call diversity in wild orange-fronted parakeet pairs. Aratinga canicularis Anim Behav. 2006;71:1141–54. doi: 10.1016/j.anbehav.2005.09.011. - DOI
    1. Soltis J, Leong K, Savage A. African elephant vocal communication II: rumble variation reflects the individual identity and emotional state of callers. Anim Behav. 2005;70:589–99. doi: 10.1016/j.anbehav.2004.11.016. - DOI
    1. Arnold BD, Wilkinson GS. Individual specific contact calls of pallid bats (Antrozous pallidus) attract conspecifics at roosting sites. Behav Ecol Sociobiol. 2011;65:1581–93. doi: 10.1007/s00265-011-1168-4. - DOI
    1. Marler P, Hobbet L. Individuality in a long-range vocalization of wild chimpanzees. Z Tierpsychol. 1975;38:97–109. doi: 10.1111/j.1439-0310.1975.tb01994.x. - DOI - PubMed

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