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

Abstract

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.