Lemurs, primates found only on Madagascar, possess a rich and complex system of vocal communication. Their calls are diverse, forming an auditory landscape that governs their social lives and survival in the dense rainforests. The sounds vary dramatically between species, ranging from soft purrs to loud, haunting songs. Understanding what a lemur sounds like requires examining the full range of acoustic properties they employ.
The Acoustic Spectrum of Lemur Calls
Lemur vocalizations span a wide spectrum, encompassing tonal and noisy, high-frequency and low-frequency sounds. They use short, high-frequency sounds (clicks, chirps, trills) for short distances. Conversely, deep, low-frequency sounds (howls, moans, roars) travel farther through dense vegetation. The black-and-white ruffed lemur is known for its loud, complex “roar-shriek” vocalizations.
The unique structure of the lemur larynx contributes significantly to these sounds. All Madagascan lemurs possess an additional pair of vocal folds, an anatomical adaptation that lowers the frequency of their calls. This allows the animal to sound physically larger than it is, projecting an exaggerated size advantageous in territorial and competitive interactions.
Scientists categorize sounds based on acoustic features like duration, tonality, and harmonic composition. Monosyllabic calls are simple, while multisyllabic calls are often grouped into complex sequences or contagious choruses, such as synchronized howling. Varying these properties allows lemurs to create a nuanced vocabulary.
Decoding the Message Function and Context
Lemur calls serve various functions tied to their social structure and environment, with the purpose defining the acoustic characteristics. Loud, long-duration calls are used for territorial defense and long-distance communication to announce a group’s location or presence. For instance, non-infant male ring-tailed lemurs emit a distinct “howl” as an advertisement call, often met with counter-calling from females. This communication is essential for maintaining group cohesion and warning neighboring groups.
Alarm calls are short, sharp sounds used to warn of predators, and some species demonstrate functional reference. Ring-tailed lemurs use different calls to distinguish between aerial threats (like a harrier-hawk) and ground threats (such as the fossa). The specific sound prompts distinct, appropriate escape behavior in other group members.
Affiliative and social calls are soft, close-range vocalizations used to maintain bonds within the group. Sounds like low moans, purrs, and quiet “hmm” vocalizations are used during grooming or feeding. In ring-tailed lemurs, the soft “hmm” call is used by low-ranking males to signal nonaggressive intent and maintain proximity to tolerant individuals.
Species Spotlight Unique Vocalizations
The diversity among lemur species results in unique vocalizations. The Indri, one of the largest lemurs, is famous for its complex, long-duration “songs” often described as haunting or whale-like. These songs are intricate duets and choruses used for territorial defense and to find lost family members. Indri songs display categorical rhythms, with intervals following patterns common in human music, such as the 1:1 rhythm or the 1:2 rhythm found in songs like Queen’s “We Will Rock You”.
The Ring-Tailed Lemur has one of the largest vocal repertoires, comprising up to 22 different adult call types. Beyond howls and moans, they exhibit sounds including “yips,” “cackles,” and a high-arousal “wail” that promotes group cohesion under stress. This extensive vocabulary highlights the link between social complexity and communication repertoire size.
The Sifaka is named after its characteristic vocalization. The Coquerel’s Sifaka emits a distinct, high-pitched, explosive bark that sounds like “shif-ak” or “sh-frrrr-k!” This unique bark functions as a “lost call” or contact call, used to locate group mates if they become separated. The Sifaka’s call is a clear example of a species’ name derived directly from its recognizable communication signal.