During summer months, before the monsoons, the males are easily detected by their repeated calls but can be difficult to spot. The call is a loud screaming three-note call, repeated 5 or 6 times, rising in crescendo and ending abruptly. It is heard throughout the day and frequently during moonlit nights. The calls of females are a series of grating notes. Common hawk-cuckoos feed mainly on insects and are specialised feeders that can handle hairy caterpillars. Caterpillar guts often contain toxins and like many cuckoos they remove the guts by pressing the caterpillar and rubbing it on a branch before swallowing it. The hairs are swallowed with the caterpillar and are separated in the stomach and regurgitated as a pellet.