Less colorful birds and animals that inhabit the rain forest tend to rely on forms of signaling other than the visual, particularly over long distances.
The piercing cries of the rhinoceros hornbill characterize the Southeast Asian rain forest, as do the unmistakable calls of the gibbons. In densely wooded environments,sound is the best means of communication over distance because in comparison with light, it travels with little impediment from trees and other vegetation. In forests, visual signals can be seen only at short distances, where they are not obstructed by trees. The male riflebird exploits both of these modes of signaling simultaneously in his courtship display. The sounds made as each wing is opened carry extremely well over distance and advertise his presence widely. The ritualized visual display communicates in close quarters when a female has approached.A.Animals that have different predators at different times of day change color to avoid being detected.
B.To be noticed, an animal may draw attention to the contrast between its colors and the colors of its environment.
C.Yellow and green are the most common colors found in the rain forest.
D.To escape notice, an animal may move or change color so that its color pattern is not visible.
E.Animals must have signals for aggression as well as to indicate readiness to mate.
F.An animal may use sound rather than color to attract attention, because sound signals are not hindered by light conditions.
