How do Elephants Say Hello to each other?

When elephants reunite with friends, they greet each other with ear flaps, rumbles and other deliberate sounds and gestures, new research shows.
The study, which was published in the journal Communications Biology, suggests that elephants are communicating intentionally and that they tailor their greeting depending on what other elephants are doing. For example, when another elephant was already paying attention, elephants were more likely to use visual gestures; otherwise, they were more likely to use touch.
Scientists already knew that elephants communicate from up to miles away using deep rumbles that are too low for humans to hear but that their species' massive ears pick up with ease. And their long trunks come with an excellent sense of smell: Elephants can sniff out age, kinship and even social groups - among both elephants and people. Compared with humans, though, elephants' eyesight is relatively poor.
Previous elephant communication research has tended to focus on sound and smell separately rather than on how those and other senses might work together.
This study is unique in how seriously it tackles the concept of multi-modal communication," meaning communication that involves multiple senses at once.
Elephants only tend to greet other elephants that they know and like, so an important first step was to figure out which elephants in the group were already close.