The hippopotamus is a grazing mammal of great importance to many African ecosystems. Every day at sunset, these herbivores emerge from rivers and lakes to feed on dry land. They can swallow some 70 kg of grass during the night and then return to the water in the early morning to laze there in groups during the day, far from enemies and sheltered from the scorching sun. During this time, they digest the grass and expel their droppings into the water.
They carry half a metric ton of silicon daily into waterways, an important nutrient for aquatic plants and other sometimes microscopic animals.
As planet Earth becomes more and more inhospitable for large animals, it is essential to better understand their lifestyles in order to try to preserve them.explain in a press release the authors of this work associated with the universities of Jean Monnet Saint-Étienne, Lyon, and Lisbon.
Hear the difference
In their experiments carried out in the Maputo Special Reserve, in Mozambique, the scientists broadcast sound signals in the presence of groups of hippos to observe their reactions to an individual’s vocalizations:
- of the same group (familiar);
- from a group from the same (neighbouring) lake;
- of a remote (foreign) group.
Researcher Nicolas Mathevon and his colleagues found that the vocalizations of a foreign individual induce a stronger behavioral response than those produced by the other two stimuli, showing that
hippos are able to identify their peers based on voice signatures.
In addition, these works show that
hippopotamus groups are territorial entities that behave less aggressively towards their neighbors than towards strangers.
This new knowledge may be considered during the transfer of hippopotamuses which is sometimes practiced to maintain populations above critical levels.
Before transferring a group of hippos to a new location, a preliminary precaution could be to broadcast their voices from a loudspeaker to the groups already present so that they get used to them and their aggressiveness gradually decreases.note the researchers, whose details of the work are published in the journal Current biologyHave (New window)Have (in English).