Are there individual differences in dog calls before two months of age?
Résumé
While recent studies of dog (Canis familiairis) vocal communication have considerably improved our understanding of the intra- and inter-specific function of this domestic species’ vocalisations, these studies have largely focussed on the vocal behaviour of adult dogs. As such, the origins and development of static (e.g. size, age, dominance…) and dynamic (e.g. motivation or emotions) vocal cues remain poorly understood. Here, we investigated whether the fundamental frequency (F0) of puppies’ isolation calls provides static cues to age and body weight before two months of age. We recorded whines of Beagle puppies (N=26 from 5 litters) during their 3rd,6th and 9th week of life. We recorded 2800 whines while individual puppies were temporally isolated from their mothers and littermates. We then analysed the F0 mean, F0 range and F0 contour of these calls and used linear mixed models to test the effect of age and body weight on these parameters. Preliminary results indicate that, while (within each litter) the mean F0 is negatively correlated with body weight at 3 weeks of age, this effect disappears at 6 and 9 weeks of age. Our preliminary investigation thus suggests the F0 mean may provide mothers with reliable information on puppy condition during the breastfeeding phase. Future work will investigate the possible function of this information, as well as the longitudinal trajectories in call F0 until adulthood.