“I’m here. Where are you?” seems to be the gist of many of the vocalizations blaring from herds of hoofed mammals. In animals living in groups, the ability of mother and newborns to recognize each other by call is essential for offspring survival. But studies determining whether such recognition lasts after weaning have rarely been undertaken. A small herd of Pygmy goats at a farm in Nottinghamshire, England, offered investigators a chance to test mother goats’ memories of contact calls in this species that is quick to bleat and blat.
Using playbacks, Elodie F. Briefer of Queen Mary University of London and two colleagues had previously shown mutual vocal recognition of nannies and their kids at one and five weeks after birth. In this study, the team exposed the nannies to the same recordings of the five-week-old kids after another eleven to seventeen months had passed. By this time, the kids had been weaned for from seven to thirteen months, and their nannies were nursing new kids. The researchers also played recordings of familiar kids of other females. They measured how quickly and how long each nanny looked at the source of the playback and how many vocalizations they made in return.
The strongest responses of the nannies were to their own kids at five weeks after birth, but they responded more to the calls of their previous kids than to those of familiar kids from other females. Long-term vocal memory is probably common in social mammals, the authors maintain. In goats, the ability may prevent inbreeding of mothers and sons and strengthen the bonds of mothers and daughters in goat society, which is largely matriarchal. (Proceedings of the Royal Society B)