Ecological factors further reinforce the importance of this specialized anatomy, particularly in the complex riparian and mangrove habitats where these monkeys reside. The loud, amplified calls generated by the nose are essential for communication in these densely vegetated and often noisy environments. The ability to project a clear, deep call across the sounds of rushing water and rustling leaves ensures that the male can effectively coordinate the movement of his group and maintain cohesion, which is crucial for safety and efficient foraging.
