Sound recordings
For his research, the biologist recorded the sounds of seal pups at Sealcentre Pieterburen (currently located in WEC Lauwersoog), where they were temporarily sheltered to regain their strength. Each day, he recorded ten to fifteen minutes of audio from 64 pups. ‘In the wild, pups call for their mothers when they are hungry or separated.’ Each pup produces unique calls – a kind of vocal signature that allows mothers to recognise their own young shortly after birth. This is useful when mothers return from hunting and need to locate their pups on the beach. ‘After spending so many hours with the pups, I could easily recognise at least half of the calls,’ the researcher laughs.
His research shows that the calls of pups housed close together gradually become more similar – comparable to local accents in humans. In an experiment in which he played pup calls through a loudspeaker, Koen de Reus also observed that the pups waited for their turn before vocalising. ‘Just like humans, who wait until someone else has finished speaking’ he explains. ‘It seems like seals are far more social animals than we previously believed.’
