Sinharaja endemic bird flock dynamics: mixed-species foraging and sentry drongos?

Sinharaja Rainforest is globally renowned for studying mixed-species bird flocks (bird waves), where up to twelve different insectivorous bird species forage together. Flocks are spearheaded by sentinel species like the Greater Racket-tailed Drongo and Orange-billed Babbler, which maintain constant contact via alarm calls. When predatory raptors or vine snakes approach, sentries issue sharp alarm cries that cause the entire mixed flock to freeze or dive into dense cover simultaneously.