Elsevier

Animal Behaviour

Volume 153, July 2019, Pages 115-129
Animal Behaviour

Dogs' sensitivity to strange pup separation calls: pitch instability increases attention regardless of sex and experience

https://doi.org/10.1016/j.anbehav.2019.05.010Get rights and content

Highlights

  • Sex and sexual status have no effect on dogs' reaction to pup separation calls.

  • Previous parental experience has no effect on the dogs' behaviour.

  • Acoustic features (jitter, f0) of the pup calls affects the dogs' reaction.

  • Jitter of the pup calls correlates positively with the dogs' attention.

  • Pup calls' f0 negatively affects the dogs' explorative behaviours.

When separated, young offspring produce separation calls to attract their mother's attention, reduce distance between them and receive maternal care. Previous studies suggest that these calls arouse the caregiver's attention because of their special acoustic structure. Furthermore, under specific conditions separation calls can elicit an approach response even from heterospecific mothers and nonparent conspecifics depending on their sex and parental experience and the species' parental care system. Dogs, Canis familiaris, are good models because we can easily test the effects of a wide range of individual characteristics such as sex, sexual state, age, breed and behaviour traits due to a diverse dog population. Here, we assessed the reaction of sexually mature, intact and neutered dogs to strange 4- and 11-day-old dog pup separation calls, presented from a hidden speaker. We recorded the reactions of former mothers, inexperienced intact females and males and inexperienced neutered females and males to six different repeated playbacks of pup separation call bouts. We tested the effect of sex, sexual state, parental experience and age of the dogs, the fundamental frequency, call length, jitter and nonlinear phenomena ratio of the playbacks and the habituation effect of repeated playbacks. We found a positive correlation between the jitter level of the sound and the dogs' attention, while the fundamental frequency negatively affected the dogs' orientation to the speaker and the door leading to the speaker. The sex, sexual state and parental experience of the dogs did not affect their reactions towards pup separation calls. Based on these results, it seems that dogs' reactions are affected mostly by the acoustics of the separation calls, not their own individual characteristics.

Section snippets

Vocal Expression and Inner State

Acoustic characteristics of calls are affected by the caller's physical/morphological parameters and inner state. The source–filter theory describes sound production as a two-stage process in the source (larynx) and the filter (supralaryngeal vocal tract; Fant, 1971, Titze and Martin, 1994). The central structure of sound production in mammals is the larynx with two vocal folds, which determines the f0 of the calls caused by the periodicity of the opening–closing cycles of the glottis (vocal

Ethical Note

Ethical approval was obtained through the National Animal Experimentation Ethics Committee of Hungary (PEI/001/1056-4/2015). Owners completed a written consent form, which permitted them to volunteer their dogs to participate in the study.

Subjects

We initially had a sample of 162 dogs but 11 had to be excluded for various reasons: one was a hermaphrodite, one was pseudopregnant, two were neutered after having a litter, one showed distress after entering the room, three females had no puppies of their

Results

The 17 percentage variables (three of the 20 behaviour variables were excluded) were combined into six principal components (attention, stand, owner attention initiation, speaker exploration, escape and stress, and door exploration; Table 3). Model results are given below and in the Appendix.

Discussion

To our knowledge, this is the first study to examine the effects of dog pups' separation calls on adult dogs. Using a playback method, we investigated the reactions of adult intact and neutered female and male dogs with different parental experience to strange pup separation calls that varied in their acoustic characteristics (f0, call length, jitter and NLPR). Our results suggest that the dogs' behaviour was mainly influenced by the acoustic characteristics of the calls, while sex, sexual

Acknowledgments

We are grateful to all owners and their dogs for their participation in the study. We were funded by the National Talent Program (NTP-NFTÖ-16-B), the Hungarian Academy of Sciences (MTA 01 031) and the MTA TKI PPD Grant (460002). We are also thankful to the anonymous referees for their helpful comments and Dr Angela Turner for improving the language of our manuscript.

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