Young Asian elephant calves show differentiated social relationships with conspecifics

Abstract

Social relationships may increase longevity and reproductive success of individuals, thereby providing crucial benefits in social species. Adults of many social species have differentiated social relationships; however, when and how these relationships form and are maintained are often not understood. We studied spatial and behavioural interactions between young calves ([≤]6 months old) and conspecific females ([≥]5 years old) to understand social ontogeny in a wild Asian elephant (Elephas maximus) population in Nagarahole and Bandipur National Parks, southern India. We found that elephant groups with calves comprised females - mother and escort, who provided active care, and females who did not provide overt, active care - other females. Escorts, apart from coordinating their movement with the calf, provided allomaternal care by initiating positive and helpful interactions with the calf. Other females rarely initiated interactions, which were usually negative, towards calves. Primarily calves, rather than conspecific females, initiated and terminated proximity contacts and behavioural interactions. Calves were near and interacted similarly with their mothers and escorts, under feeding, resting, and social contexts, and almost never interacted with other females. Similarly, we found remarkable similarities between mothers and escorts in their behaviours towards calves, with the primary difference being that escorts did not provide milk. Our results suggest that calves begin to form differentiated social relationships from a young age. The presence of calves and their interactions with escorts might result from existing close social relationship between mothers and escorts or may establish new relationships. Allomaternal care may also reinforce relationship differentiation in such social species. As calf-escort interactions involved behaviours that may potentially be helpful in protection and feeding skill acquisition, the development and survival of calves may be affected by the presence of, and interactions, with allomothers. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=197 HEIGHT=200 SRC="FIGDIR/small/650831v2_ufig1.gif" ALT="Figure 1"> View larger version (83K): org.highwire.dtl.DTLVardef@1564ccdorg.highwire.dtl.DTLVardef@cc276aorg.highwire.dtl.DTLVardef@12fc57corg.highwire.dtl.DTLVardef@14e7a8e_HPS_FORMAT_FIGEXP M_FIG C_FIG We studied spatial and behavioural interactions between young calves ([≤]6 months old) and conspecific females to understand social ontogeny in a wild Asian elephant population. We found differentiated relationships between calves and conspecifics even at a young age. Escorts, who showed coordinated movement with calves, engaged in other positive interactions with calves, with remarkable similarity to the mothers, whereas other females rarely initiated such interactions. Escorts are thus allomothers in the Kabini elephant population. Calves, rather than conspecifics, initiated and terminated most of the proximity and behavioural interactions and were thus precocial in forming new relationships.