Mutual mother-offspring vocal recognition in an ungulate hider species (Capra hircus)

Parent-offspring recognition can be essential for offspring survival and important to avoid misdirected parental care when progeny mingle in large social groups. In ungulates, offspring antipredator strategies (hiding vs. following) result in differences in mother-offspring interactions, and thus different selection pressures acting on the recognition process during the first weeks of life. Hider offspring are isolated and relatively stationary and silent to avoid detection by predators, whereas follower offspring are mobile and rapidly mix in large social groups. For these reasons, hiders have been suggested to show low offspring call individuality leading to unidirectional recognition of mothers by offspring and followers high offspring call individuality and mutual recognition. We hypothesised that similar differences would exist in hider species between the hiding phase (i.e. unidirectional recognition) and the phase when offspring join social groups (i.e. mutual recognition). We tested these predictions with goats (Capra hircus), a hider species characterised by strong mother-offspring attachment. We compared the individuality of kid and mother calls, and the vocal recognition ability, during the early phase of life when kids are usually hidden and later when kids have typically joined social groups. Contrary to our predictions, we found that both kids and mothers had individualised contact calls and that mutual recognition existed even during the hiding phase. The large differences in the duration of the hiding phase and in the rate of mother-offspring interactions (possibly partially driven by domestication in some species) probably cause variations among hider species in the mother-offspring recognition process.