Vocal production mechanisms in ruffed lemurs: a Prosimian model for the basis of primate phonation

The island of Madagascar is one of the planet's foremost biodiversity hotspots and it is threatened with large-scale destruction by unsustainable human activities. The ruffed lemur, like all other lemurs, is endemic to Madagascar and inhabits the eastern rainforests of the island. A captive breeding project for this species has been underway since the Sixties and lead to a relatively great population of captive ruffed lemurs. Part of this population was recorded for the purpose of this study and phonetic analysis of the ruffed lemur calls is presented in this paper. As reported from studies on human and non-human primate vocal communication, ruffed lemurs show acoustic cues on actual (or even exaggerated) vocalizer body size when emitting inter-group and agonistic vocalizations. The vocal repertoire of V a r e c i a sp. also features submissive, affinitive and pre-copulation calls, showing different formant patterns that contradict the use of the uniform, or flared, tube system as a valid model of non-human primate phonation.