Calves function as social magnets in a species with high fission-fusion dynamics, the Asian elephant

Abstract

Individuals living in fission-fusion societies may face unique challenges in maintaining social relationships, as the repeated fission of social units can limit opportunities for social interaction. However, the presence of young offspring may often necessitate cooperation among individuals. To understand whether offspring promote sociality in fission-fusion species, we studied wild Asian elephants (Elephas maximus) in southern India. Using nearly 5900 female group sightings collected over 9 years, we tested whether calf presence predicted female group size and associations. The numbers of adult, young adult, and subadult females in groups were 2-2.5-fold higher in calf presence than absence, which may facilitate collective defence of calves. Furthermore, the number of females without their own dependent offspring, who often provide allomaternal care, was also higher in calf presence than absence. Social network analysis revealed that adult females formed more numerous and stronger associations in calf presence than absence, which may facilitate consistent allomaternal care. Our results thus suggest that the need to protect calves and to provide allomaternal care likely promote sociality among female elephants. We propose that dependent offspring may function as social ties in fission-fusion species, contingent upon the prevailing conditions and the socioecological pressures that have shaped their social systems.