Female elephants rumble to say 'let's go!' Namibian study shows males do too, a sign of unexpected social bonds

In elephant family groups made up of related females and their young, it is clear that the animals produce vocal sounds to coordinate action. This happens when it's time to leave a waterhole, for example. The matriarch or dominant female steps away from the waterhole and turns to the direction she intends to move in. Then she flaps her ears as she makes a short call referred to as the "let's go" rumble.