Animals "Let's go!": Bull elephants call their mates

In family groups, the females call the shots. But when the bulls are among themselves, they have to coordinate themselves. Then they grumble with each other.

"Grrrrrrrrrrrrrrrrrrrr": humans simply hear a deep, drawn-out rumble, but male elephants understand something like this: "Hey guys, let's move on!" A research team in the USA has now been able to document these departure calls in bull elephants for the first time.

Until now, biologists thought that only female elephants in family groups made these calls. However, in recent years, numerous recordings have been made at a waterhole in Etosha National Park in Namibia in which elephant bulls in close-knit male groups let out a very similar growl.

Each bull waits until its predecessor is almost finished

As the researchers write in the specialist journal "PeerJ", the groups do not stop at one call. Several other bulls in the group respond with similar, extremely low-frequency growls. They wait until the previous bull has almost finished its sequence. According to the study, the whole process is very ritualized. Finally, they move off together and leave the waterhole.

"We were amazed that male elephants, which usually only form loose social bonds, coordinate their voices in such a sophisticated way to get moving," explains first author Caitlin O'Connell-Rodwell, who conducts research at Stanford University and Harvard Medical School, among others. The communication of the bulls is more complex than previously assumed, explained the scientist.

Elephant communication from 13 years of research

O'Connell-Rodwell, who has been researching elephants in the wild for 30 years, first recorded the elephant walking in 2004. Between 2005 and 2017, further recordings were collected at the Mushara waterhole - including not only sounds audible to humans, but also very low-pitched sounds in the infrasound range.

The researchers believe that the male elephants learn this type of communication from older female elephants. "They grew up in a family where all the female leaders use this ritual," says O'Connell-Rodwell. "We believe that as they grow up and form their own groups, they adapt and use these learned behaviors to coordinate with other males."

Older bulls act as mentors

The first go-call is given by the most social bull, who is sometimes also the dominant bull in the group. These animals play an important role in the group because they promote cohesion and stability. They are often a kind of mentor for younger bulls, says O'Connell-Rodwell. "The older males are willing to take them under their wing, guide them, share resources with them and share in their emotional ups and downs."