Why do many rainforest animals use sound more than sight to communicate?

In the dense environment of a tropical rainforest, animals often rely on sound rather than sight for communication because the thick vegetation acts as a significant physical barrier to visual signals.12

The primary reasons for this reliance include:

• Obstruction by Foliage: Rainforests are characterized by complex, multi-layered vegetation, including dense undergrowth, lianas, and a thick canopy. Intervening obstacles like leaves and branches easily block the straight-line propagation required for visual signals, making them ineffective over even short distances.21
• Efficiency of Sound: Sound signals are better suited for these environments because they can propagate efficiently around obstacles such as trees and foliage. While visual signals are easily obscured, sound allows animals to maintain contact and convey information despite the physical density of the forest.12
• Environmental Constraints: In the lower strata of the rainforest, where light is filtered by the upper canopy, visual communication becomes increasingly difficult. Sound remains a reliable medium for signaling territoriality, alarm, or the presence of food, even when visibility is limited.2134

Consequently, evolution has favored the use of vocalizations in these habitats, as sound signals are less likely to be blocked by the structural complexity of the forest.12