Male elephants 'rumble' when it's time to move on

Picture this - you're playing outside at a friend's house, enjoying the sunny weather and being carefree when you hear a familiar call.

It's your parent telling you it's time to go.

A new study suggests its not just humans who do this.

Male elephants signal to their group that it's time to move on by letting out a "sophisticated" deep growl, the research suggests.

The animals' behaviour was documented by scientists from Stanford University and other institutions.

The elephants were observed at the Mushara waterhole in Etosha National Park, Namibia and the distinctive rumble was first recorded in 2004.

From 2005 to 2017, the team collected data at the waterhole, mainly during the dry seasons.

Researchers found the deep rumbles were started by male elephants which were the most dominant and well established in their close-knit groups.

They also say the findings are surprising because this behaviour was previously thought to only be done by female elephants in family groups.

So how does it actually work?

The new study suggests the lead elephants in group use sounds to signal to the group when it's time to move on

After getting some much needed hydration at a waterhole, a senior bull elephant will lift his head, turn away, and let out a low rumble.

The deep growl may sound just like any of his other noises to humans, but it's actually one which sends a clear message to the other elephants that it's time to go.

One by one, the elephants respond with their own rumbles and the group then moves on to their next stop.

"We were astonished to find that male elephants, typically considered to have loose social ties, engage in such sophisticated vocal coordination to trigger action," said the study's lead author Caitlin O'Connell-Rodwell who is a research associate at Stanford University's Centre for Conservation Biology.

"These calls show us that there's much more going on within their vocal communication than has previously been known."

The researchers studied the type of sounds the elephants made, making note of which elephants first began the rumbles, how the others responded, and the sequence of events leading to the group moving on.

The researchers say male elephants may have learned the rumbles from female elephants when they are young

The so-called "let's go" rumbles are very similar to those previously recorded in female elephants, and the researchers suggest that male elephants likely learn the behaviour when they are young.

"They grew up in a family where all the female leaders were engaging in this ritual," Dr O'Connell-Rodwell explained.

"We think that as they mature and form their own groups, they adapt and use these learned behaviours to coordinate with other males."

As well as making key sounds used to signal a move, the study also reveals some dominant male elephants play other important roles within their social groups, helping to maintain cohesion and stability.

Dr O'Connell-Rodwell explained that these animals essentially take on "mentoring" roles.

"They care about these young whippersnappers who are very needy and always wanting to be in physical contact," she said.

"The older males are willing to take them under their wing, to guide them, share resources with them, and partake in their emotional ups and downs."