Auditory communication is almost universal among mammals and can include nonvocal as well as vocal sounds. Mountain gorillas, for instance, beat their chests with cupped hands to intimidate enemies, while banner-tail kangaroo rats make the ground vibrate when they drum it with their hind feet to mark territory, compete for mates or distinguish friend from foe. Vocal style may also be distinct for each individual. For example, Southeast Asian gibbons can identify the sex of a caller, their family and ultimately individual identity. Calls typically indicate:
- Dominance and submission: Primates and carnivores often use sound to signal who's in and who's out. For example, squirrel monkeys have a repertoire of growls and grunts to indicate social status within the group.
- Alarm: Many primates signal alarm with their cries. Vervet monkeys even have a range of different alarm shrieks to indicate particular types of predators.
- Territoriality: North American woodchucks use high-pitched squeaks and whistles to signal when their territory is being invaded.
- Mating: Some mammal species employ sound as they court. For example, Asian elephants emit infrasound rumblings to indicate reproductive receptivity.