Tornado-ing feces from your rectum might be a pretty controversial way to respond to strangers as a human, but for hippos it’s apparently the go-to. That’s a takeaway from new (and crucial) research into the social habits of hippopotamuses, which uncovered that these bodacious danger cows can recognize each other's calls.

Upon recognizing the “wheeze honk” of neighboring hippos, they will respond in a chorus of honky honky hippos. However, if they don’t recognize the call they greet strangers with a tornado of potent poop (as demonstrated here). Quite the statement.

Published in the journal Current Biology, the new paper concludes that hippos are capable of recognizing each other’s voices and will alter their behavior accordingly. Familiar hippos will be on the receiving end of a friendly honk while the more aggressive dung-spraying poo-nado reply is reserved for strangers.

“We found that the vocalizations of a stranger individual induced a stronger behavioral response than those produced by individuals from either the same or a neighboring group,” said Nicolas Mathevon of University of Saint-Etienne, France, in a statement.

“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 their neighbors than toward strangers.”

_{Sound on for a good honk.} 

To reach their conclusions, the team behind the research focused on a group of hippos in the Maputo Special Reserve in Mozambique where several lakes contain hippos. They recorded calls from each hippo group and then played these back to other groups to see how the animals would respond.

When hearing a familiar call they’d respond vocally, whereas strangers’ calls elicited a dung-spraying response. Beyond be a little mucky, poo-flinging is a behavior linked to marking territory among hippos. Quite effective if you imagine your response to an Airbnb listing with visible feces in the preview shots.

The findings could have implications for hippo management in findings ways to reduce aggression when relocating groups of animals.

“Before relocating a group of hippos to a new location, 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,” said Mathevon. “Reciprocity, in which the animals to be moved become accustomed to the voices of their new neighbors before they arrive, could also be considered.”

The team’s next steps hope to crack the hippo honk code to establish what characteristics help these animals to recognize who to say "hey" to, and who’s getting a face full of feces.