Mammals typically produce sound through vocal cords, which are folds of tissue located within the larynx, often referred to as the voice box. These tissues vibrate as air expelled from the lungs passes over them, creating the sound waves that form vocalizations. The tension and length of these vocal cords can be adjusted, allowing for a diverse range of pitches and volumes. While this mechanism is fundamental to communication across most mammalian species, one notable exception challenges this common understanding.
The Giraffe’s Silent Secret
The giraffe, Giraffa camelopardalis, stands as the world’s tallest mammal, known for its towering height and distinctive spotted coat. For many years, giraffes were widely considered silent creatures, a misconception stemming from the rare observation of audible sounds. This perception was often attributed to the belief they lacked vocal cords or that their unique anatomy prevented vocalization.
While giraffes do possess a larynx and vocal folds, their anatomical structure presents significant challenges for producing loud or varied sounds. Their trachea, extending 2 to 2.4 meters (6.6 to 7.9 feet), requires air to travel an immense distance to the vocal folds. This extended, narrow pathway, combined with limited lung capacity, reduces airflow velocity and pressure, making robust vibrations difficult.
Despite these biomechanical hurdles, giraffes produce a range of sounds, many at frequencies beyond human hearing or very subtle. These sounds, combined with physical characteristics and behaviors, enable a complex communication system. The infrequent nature of their audible vocalizations contributed to the long-held belief in their silence.
Beyond Vocal Cords: Giraffe Communication
Giraffes employ diverse communication methods beyond typical vocalizations. They use infrasound, low-frequency sounds below 20 hertz. While some studies suggest long-distance communication, other research indicates some low-frequency vocalizations, like nocturnal “hums,” are at the lower edge of human hearing.
These “hums,” often detected at night, are sustained and frequency-modulated, with an average frequency around 92 hertz. Their purpose is still under investigation, but scientists speculate they might be used for social bonding, alarm calls, or courtship when visual communication is limited. Other occasional audible sounds include snorts, grunts, hisses, and moans, which may convey warnings or discomfort.
Beyond sound, body language plays a significant role. Their height and flexible necks are utilized for various visual signals. A giraffe’s posture can convey alertness, dominance, or submission, such as holding its neck high or lowering it to indicate displeasure. Head bobbing can signify excitement or agitation, while slow, rhythmic nodding may be used to calm calves or during peaceful social interactions.
Physical contact, though less frequent than in some other social mammals, also serves communicative purposes. Neck rubbing and nudging are common tactile interactions, particularly between mothers and calves for bonding, or among females. Male giraffes engage in “necking,” a form of sparring to establish dominance.
Chemical signals contribute to giraffe communication. They possess scent glands on their hooves, leaving chemical markers as they move. Males use these scents to assess the reproductive status of females, while females may use them to locate and track their calves and herd members. These messages allow giraffes to gather information about others in their territory.