Hippopotamuses are very vocal animals, although we know little about why they make so much noise.
They often call and respond to each other, like a conversation.
According to new research, hippos can even recognize their pals’ voices when they’re recorded and played by a loudspeaker.
Nicolas Mathevon
In a paper published this week in the journal Current Biology, researchers tracked hippos’ reactions when they listened to calls from familiar and unfamiliar peers.
For five of the seven groups studied, the researchers played back calls from three types of individuals:
- Hippos from the same group
- Neighbor hippos living in the same lake
- Complete strangers
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They focused on one type of call dubbed the “wheeze honk” — a low rumble that travels over long distances. This call is thought to play an important role in hippo social bonding.
When the researchers played a recorded wheeze honk over a speaker, the hippos talked back.
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Here’s one group responding to a call:
The hippos pause for a few seconds after listening, then respond back.
Nicolas Mathevon
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When the voices of unfamiliar hippos played over the speaker, the animals listening would respond with more aggression than they did with the calls of group members or neighbors.
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Knowing this, researchers say, could potentially help with hippo conservation efforts.
Hippos are recognized as a threatened species, and their numbers have dramatically decreased in recent years.
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Relocating hippos can be a challenge because they are incredibly territorial.
But finding a way to make hippos more comfortable with strangers could start with exposing them to the outsider’s voice.
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“One precaution might be to broadcast their voices from a loudspeaker to the groups already present so that they become accustomed to them and their aggression gradually decreases.”