While there are many different specific personality types, people are often categorized as either introverted or extroverted. Some like to keep to just a few close friends, rarely leaving their small comfort zones, while others are more outgoing, collecting friends wherever they go; most of us fall somewhere the middle. But we’re not the only mammals with this type of social diversity. Researchers in Sri Lanka have now found that many female Asian elephants—previously believed to be kind of antisocial—are social butterflies, changing their circle of friends as the seasons pass. Moreover, they maintain close ties with pals even after extended periods of separation.

In an Asian elephant society, females and calves stick together in groups of a few individuals, called herds, while males roam about more independently, doing male things. These small bands are part of much a larger group. In the new study, published in the journal BMC Ecology, researchers wanted to see how the relationships of individual female elephants changed over time, so they stalked nearly 300 pachyderms for five seasons in the Udawalawe National Park in Sri Lanka.

As expected, Shermin de Silva, a behavioral ecologist at the ...