Hippos are animals that use their voices a lot to communicate with each other, and this can be heard over long distances. A study reveals that these mammals are able to recognize each other’s voices, and that their response is influenced by that same reason. Thus, the way hippos respond varies depending on whether it is a friend or a stranger.
“We discovered that the vocalizations of a stranger induce a stronger behavioral response than those produced by individuals from the same group or from a neighboring group”, explains Nicolas Mathevon in the scientific journal Science.“In addition to showing that hippos are able to identify conspecifics based on vocal signatures, our study highlights that hippo groups are territorial entities that behave less aggressively toward neighbors than toward strangers.”
While working at the Maputo Special Reserve, in Mozambique, the researchers recorded the calls of each of the hippo groups. To test their reaction to the voices from the different groups – family, neighbors or strangers – they subsequently replayed all the recordings. The main reactions of the hippos were to respond, to move closer to the group, or to spray excrement. When they heard voices from a stranger group, the hippos responded aggressively and sprayed excrement, in order to mark their territory.
This discovery sheds new light on how these animals communicate, but also on the need for caution when bringing hippo groups together. “Before relocating a group of hippos to a new location, it may be prudent to broadcast their voices over loudspeakers so that the groups already present become accustomed to them and their aggression gradually decreases,” suggests the author.
