Giraffes Spend Their Nights Quietly, Constantly Humming

Not so silent after all


For years, experts believed that giraffes didn’t really communicate vocally. After all, many zookeepers thought, it would be pretty difficult to force enough air past their voice boxes to make any sort of sound aside from a snort, considering the length of their necks. But as it turns out, giraffes spend their nights humming to each other.

Since it would take a lot of airflow to make a loud sound from a giraffe’s 13-foot-long trachea, researchers believed that giraffes had no form of vocal communication and instead relied on their keen sense of sight. But according to a new study by researchers from the University of Vienna, giraffes do communicate vocally after all – it’s just that the sounds they make are so low that it’s hard for humans to hear them, Gwen Pearson writes for Wired.

Initially, the researchers wanted to test a long-standing theory that giraffes could “talk” using infrasonic frequencies too low for the human ear, much like elephants and some other large mammals do. To answer the question, they spent almost 1,000 hours recording giraffes at three different European zoos and painstaking analyzed the waveforms by sight, looking for patterns. While they didn’t find any evidence of the giraffes using infrasound, the scientists realized that the giraffes would spend their nights humming, Karl Gruber reports for The New Scientist.

“I was fascinated, because these signal have a very interesting sound and have a complex acoustic structure,” study author Angela Stöger tells Gruber. “These results show that giraffes do produce vocalizations, which, based on their acoustic structure, might have the potential to function as communicative signals to convey information about the physical and motivational attributes of the caller,” the researchers concluded in the study.

Because giraffes seem to only hum at night, Stöger and her colleagues have yet to figure out whether it correlates with any behavior or if it’s just snoring. However, it’s possible that, like other large mammals, the humming might be used to communicate all sorts of information from age, gender, social dominance and sexual arousal, Alison Eck writes for Nova Next. While they may not know exactly what the hums mean, hopefully the scientists have the patience to spend what could be another thousand hours listening to find out.

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