Scientists have long thought that giraffes were silent animals, but a new study shows that giraffes do in fact make a specific sound. Published in the journal BMC Research News, the new study suggests that giraffes my not be so quiet after all.
Three researchers from Germany and Austria conducted the study in three different zoos from Europe, and gathered almost 1000 hours of audio material. After analysing it they observed that giraffes did not communicate by using vocal behaviours or contextual calls.
“Although giraffes do have a well-developed larynx and laryngeal nerves, it was long suggested that due to the long neck, giraffes might have problems to produce an air-flow of sufficient velocity to induce self-sustained vocal fold vibrations,” said Angela Stoeger, a researcher at the University of Vienna and co-author of the study.
The only instances of giraffes vocalizing to one another, were when newborns got separated from their mothers. Scientist believe that is not consistent communication, but rather an instinctual loud noise that works like an alarm. In the case of other hoofed animals, vocalization in very important for recognition and for creating bonds.
Scientists believed that giraffes communicated on very low-frequency (infrasound), that us humans could not hear. The new study may actually prove that was a false assumption.
The study shows that as soon as the night falls, the giraffes start humming. The vocalizations have only been recorded at night. Zoo keepers stated that they never heard the humming during the day, Angela Stoeger said.
The hum occurs at a very low frequency of (~92 Hz), which makes it difficult for humans to hear. Perhaps that is the reason why the zoo keepers were unable to hear it.
The researchers are uncertain whether this is an actual means of communication. Stoeger believes that giraffes actually hum in order to reassure one another that they are standing nearby, especially at night.
Karl Gruber, a freelance scientific writer, science communicator, and biologist, says that the local residents have picked up on the low-frequency sounds coming from the Paignton Zoo in south west England, and that they are not happy about it.
However, Stoeger believes that it is highly unlikely that people would hear the low frequency hum coming from the giraffes several houses away.
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