Wheeze-honk of stranger hippo causes resident hippo to present its bottom and sprinkle poop with its tail

by MikeB · January 25, 2022

Hippos mark territory with poop. It reminds me of cats actually. But hippos only mark territory by spraying poop with their tail when they are confronted with a hippo that is a stranger. When they hear the wheeze-honk of a hippo they have not heard before they charge off in the direction of the sound, turnaround and present their bottom to the stranger and defecate. They use their tail to sprinkle it as far as they can. It spreads the muck around a bit like a farmer spreading fertiliser over their crops. A muck spreader.

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Hippo marking territory to ward off a stranger by defecating and at the same time whizzing their tail around to spread the faeces as far as possible. The photograph is in the public domain.

A scientific study discovered this interesting behaviour. They found that the wheeze-honk of familiar hippos was acceptable to resident hippos. For example, when an individual in their immediate social group vocalised, they didn’t respond. And neither did they respond to calls of near neighbours because they were accustomed to those sounds and the hippos who made them.

It was just the wheeze-honking of a stranger which grabbed their attention. It seems that they regard a stranger as an intruder on their territory. They then decide to make a statement by depositing faeces on their territory in the vicinity of the intruding stranger. This is picked up by the stranger as a clear signal that they have entered the “home range” of a resident hippo. I presume they therefore turnaround and clear off.

As mentioned, this is very reminiscent of domestic cat urine-marking. And in fact, domestic and feral cats also mark with poop. The only interesting aspect of the hippo marking is that they whizz their tail around while they are defecating to spread the faeces. Pretty cool and pretty smelly at the same time. Highly effective though ?.

The information gathered by the study should help conservationist when they move groups of hippopotamuses to new locations which sometimes has to happen in the interests of conservation. It would seem that in the past, when relocated, they upset the social structure of resident hippos because the relocated group intruded on other hippo’s territory.

They expect conservationist now 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 Nicholas Mathervon from the University of Lyon/Saint Etienne in Central France who is the lead researcher on this project which was published in Current Biology.

They might also consider “reciprocity, in which the animals to be moved become accustomed to the voices of their new neighbours before they arrive”.