A shrinking population naturally makes for a smaller network, so the team checked whether this was just a numbers game. They looked at a population of 59 elephants seen every year of the study, which the team referred to as residents. “If it was just an artifact of the data, those core individuals should have fairly consistent relationships. But that’s not what we saw,” Madsen said. “They were changing their relationships with each other, even though they were still there.” Among these residents, the fracturing came one to three years after the decline began.
Madsen suspects some of the lost elephants were the glue holding groups together. “If you go to a city hall meeting, it’s maybe the same group of people that constantly comes in. You’re not friends with every single other person in that group, though,” she said. “There could have been some key individuals that were lost that were holding these subgroups together.”
The first ties to go were the weakest, the casual acquaintances. These weak relationships, Madsen says, could represent animals that merely tolerate each other: “Tolerance is really important in a society, especially in large animals. If they get into conflict, it could be serious.” These weak ties, researchers argue, may still be important because they can carry information between communities.
De Silva links this fracturing to the disappearing grass. “As the competition becomes more severe, your social sphere sort of shrinks,” she said. “It’s as if they’re emphasizing the quality over the quantity of the relationships.”
Flickering lights
Before the breakup, some network statistics fluctuated from year to year, which complex systems scientists call flickering. “If you have a light bulb that’s right on the edge of dying, it might start flickering,” Madsen said. “It’s on, it’s off, it’s on, it’s off. And then suddenly it dies.” Spotted early, she argues, such signals could serve as an early warning sign. “Hopefully, park managers and conservationists can detect that and intervene before the population collapses,” Madsen said.
