The giraffe has long been surrounded by the misconception that it is silent. This belief stems from the fact that their vocalizations are extremely rare and subtle in the wild, leading observers to conclude they were mute. However, scientific research has confirmed that these creatures do produce a range of sounds.
The Nocturnal Hum
The primary vocalization that has recently captured scientific attention is a deep, sustained humming sound that occurs almost exclusively at night. This low-frequency vocalization was documented by researchers analyzing hundreds of hours of audio recordings from giraffes in European zoos. The sound is described as having a rich harmonic structure and a varying duration, with an average fundamental frequency of about 92 Hertz.
This frequency is within the range of human hearing, but its low pitch and nocturnal timing mean it is easily missed by caretakers and researchers. The humming can last for several seconds and is generally low enough to be compared to a distant rumble or a low cello note. Since giraffes possess excellent eyesight and rely heavily on visual signals during the day, scientists theorize the hum may be a method of keeping contact when visibility is limited.
The sustained nature of the hum suggests a coordinated effort to communicate over darkness or perhaps a way for the herd to maintain a cohesive group structure. The challenge of producing sound over a long windpipe is likely why this particular vocalization is so low and drawn out. Its precise meaning remains an ongoing subject of study.
Contextual Sounds and Alarm Signals
Beyond the nocturnal hum, giraffes utilize a variety of other vocal and non-vocal noises for immediate communication. The most commonly observed vocalizations are short, sharp sounds such as snorts and grunts. These sounds are typically used to signal alarm or distress.
A snort is a forceful expulsion of air through the nostrils, while a grunt is a more guttural, low-pitched sound. Giraffes may also produce hissing sounds, which are generally associated with defensive behavior when they feel threatened or annoyed. These immediate vocal signals are often accompanied by specific body language, such as neck swinging or stomping.
The giraffe’s long neck and windpipe create a biomechanical challenge for sound production. The extended distance reduces the velocity and pressure of the airflow from the lungs, limiting the volume and range of sounds they can produce. This anatomical constraint is why their communication system relies on subtle or low-frequency vocalizations, and why they also communicate through mechanical noises.
Soft bleats, moans, or cough-like sounds are sometimes exchanged between a mother and her calf or during moments of irritation. Non-vocal communication also plays a major role, as mechanical noises like the sound of their feet stamping on the ground are used as clear alarm signals. These loud, percussive signals communicate danger across the open savanna without the need for a sustained vocal output.