Koalas use a range of sounds to communicate with one another over relatively large distances. There is a deep grunting bellow which the male uses to signify its social and physical position. Males save fighting energy by bellowing their dominance and they also bellow to allow other animals to accurately locate the position of the caller.
Females do not bellow as often as males, but their calls too are used to express aggression as well as being part of sexual behaviour, often giving the impression of fighting. Mothers and babies make soft clicking, squeaking sounds and gentle humming or murmering sounds to one another, as well as gentle grunts to signal displeasure or annoyance.