Loss in elephant groups leads to fractured social connections

UC postdoctoral researcher Anastasia Madsen studies the behavioral ecology of Asian elephants in Sri Lanka. Photo/Provided

Madsen and her research partners discovered that large herds stressed by drought, poaching or other losses reach a tipping point at which they fracture into smaller, isolated groups. These smaller groups are more susceptible to losses of members from the same external threats.

Led by University of California, San Diego, Assistant Professor Shermin de Silva, the study was published in the journal Science.

Unlike African elephants that live in unrelated bachelor herds and related matriarch-led families, Asian elephant society is more fluid with unrelated members coming and going. In both African and Asian species, offspring generally benefit from having more adults around to protect and care for them.

According to the study, elephants in Sri Lanka live in suboptimal habitat increasingly dominated by an inedible invasive species. And they live near people, leading to frequent deadly conflicts for both.

Researchers tracked 443 female elephants over 12 years. Initially, they identified 20 groups consisting of an average of 14 members. By the end of the study, more than two-thirds of the elephants either died or migrated out of the study area. Researchers identified 37 groups, but each contained fewer than 4 members on average.

"The biggest surprise was this fracturing in the social communities," Madsen told Science.

Madsen researches how animals use social behaviors and information to respond to demographic and environmental change. She recently joined UC Associate Professor Elizabeth Hobson's lab where they are now developing broad, generalizable models to understand causal ties between cognition, individual decisions and social networks.

Featured image at top: Asian elephants forage in a landfill in Sri Lanka. Photo/Ronny Pfeiffer/iStockPhoto