Koalas are iconic Australian marsupials, often perceived as quiet due to their cuddly appearance and preference for eucalyptus trees. Despite this docile image, koalas possess a surprisingly diverse range of vocalizations crucial for their communication. These sounds can be unexpected, challenging the perception of koalas as always silent creatures.
The Range of Koala Vocalizations
Koalas produce a variety of distinct sounds. The most recognized is the deep, guttural “bellow,” primarily emitted by males. This bellow can include snoring inhalations and belching exhalations, sometimes compared to a donkey’s bray. The pitch of these bellows can be remarkably low, reaching frequencies as low as 9.8 Hz or 27 Hz, which is significantly lower than expected for an animal of their size. This low frequency is possible due to an extra pair of vocal folds located outside the larynx, where the oral and nasal cavities connect.
Koalas also produce high-pitched sounds like “screams,” “cries,” or “wails.” These sharp vocalizations can be unsettling and are sometimes likened to a baby screaming. Koalas make softer sounds such as “grunts,” which can vary in intensity from low to harsh. They also emit gentle “squeaks,” “clicking” sounds, “purrs,” “murmuring” noises, and snarls.
Meaning Behind the Sounds
Each koala vocalization serves a specific purpose in their social interactions and survival. The deep bellow, predominantly made by male koalas, functions as a powerful advertisement during mating season. These loud calls, which can travel up to a kilometer, attract females and establish dominance among competing males. Females often show a preference for males that produce deeper, more resonant bellows, indicating larger body size and greater genetic fitness. While less common, female koalas can also bellow, using these calls for aggression or sexual behavior.
High-pitched screams, cries, and wails are associated with distress or aggression. These sounds act as warnings when a koala feels threatened or is bickering with another koala. Female koalas use a distinctive scream when rejecting an unwanted male. Grunts serve as a form of general communication, indicating mild warnings or displeasure. Male koalas grunt when moving or during aggressive encounters, with harsh grunts produced by fighting males.
The softer sounds, such as squeaks, clicking, and murmuring, are primarily used for close-range communication. Mothers and their joeys exchange these gentle noises, fostering a bond and allowing the joey to signal its needs. These varied vocalizations form a comprehensive system that enables koalas to navigate their social environment, despite their largely solitary nature.