Humans and many other social animals thrive in well-established community networks. Asian elephants are one example of a species that flourishes in groups that work together to access food and care for their young, among other social bonds.
University of California San Diego scientists in the School of Biological Sciences studying the intricacies of Asian elephant community structures have documented a troubling downturn in the population of the animals resulting in fractured social communities. Their study is published November 12 in Science.
Analyzing the social dynamics of more than 440 wild female Asian elephants over 12 years at the Udawalawe National Park in Sri Lanka, the researchers studied key shifts in the demographics of the elephants that seemed to trigger social communities becoming smaller and more isolated.
"We found that gradual accumulation of losses from turnover preceded sudden change in the social networks among females in a wild population of Asian elephants," the researchers explained in the study, which was led by Postdoctoral Researcher Anastasia Madsen from the laboratory of Associate Professor Shermin de Silva in the Department of Ecology, Behavior and Evolution. de Silva also serves as president and founder of the conservation nonprofit Trunks & Leaves Inc.
The researchers' analysis indicates a social structure tipping point. As the number of elephants in the population decreased over time, due to a combination of likely deaths, permanent emigrations of elephants and fewer incoming individuals, the population as a whole appears to have crossed a critical threshold that resulted in a shift from large, densely connected social communities, to smaller and less-connected social groupings.
"We see individual elephants leaving and possibly dying at accelerating rates, but new individuals are not coming into the population," said Madsen. "With fewer individuals in the population, those who are left will naturally have fewer relationships. However, the remaining elephants are also changing their relationships with each other."
This new dynamic is a cause for concern, says Madsen, since the animals leverage their social groups and connections to forage, acquire information and raise young.
"We can probably all relate to the feeling of social isolation brought about, paradoxically, with the advent of digital communications that seem to remove the physical constraints of needing to be in the same place at the same time," said de Silva. "But for many social species, which includes ourselves as much as elephants, we have to remember that social connectivity is very much a matter of sharing space and building relationships throughout our lives. Crucially, in order to have resilient communities, we need to be able to replace the relationships that are lost over time."
Many elephant populations are already impacted through deaths resulting from poaching and conflicts with humans. Other contributing factors may be disruptions in habitat connectivity and less food available for the elephants as ecological conditions change across the 119-square-mile park and surroundings.
The new social fracturing structure observed by the scientists may not be easily repaired, the researchers warn.
"In general, we need to be more aware of these types of tipping points where we see sudden shifts after changes have been slowly building up," said Madsen. "Once we move past the tipping point, it's much harder to go back to previous states."
The new findings will serve future studies seeking to understand shifts in animal society structures, how to detect such tranformations and the factors responsible for vulnerabilities. The study also stimulates ongoing discussions for conserving elephant populations as humans expand into areas where elephants historically thrived.
"We are gaining more evidence that studying social patterns is an important tool for us to see when things are going wrong in natural populations and, hopefully, to be able to do something about it," said Madsen.
