Purple-faced Langur - Communication

Communication

Loud calls are often used to distinguish between individual purple-faced langurs. The elements of a call fall into three categories: harsh barks, whoops, and residuals. Individuals can be differentiated by the number of phrases and residuals within a call. Calls occur more often in the morning mostly stimulated by neighboring groups and territorial battles. More calls occur during sunny periods than cloudy. The least amount of calls occur in the evening. Daytime calls usually aid in the defense of home ranges. The loud barking call, particularly of the highland form, can be mistaken for the roar of a predator such as a leopard. Calls of the purple-faced langur differ from those of any of the subspecies. Environmental characters impact call times as well as anthropogenic disturbance. Vocalization can be used to alert members of predators, attract mates, defend territory, and locate group members. Vocalization is extremely important for the use in conservation especially because they are very difficult to observe directly. Adult males are the most vocal among the entire group. Defensive whooping calls are also accompanied by intense visual and locomotive displays. Vocalizations are also helpful in determining taxonomic identification.