The dynamics of social networks among female Asian elephants

Abstract

BackgroundPatterns in the association of individuals can shed light on the underlying conditions and processes that shape societies. Here we characterize patterns of association in a population of wild Asian Elephants at Uda Walawe National Park in Sri Lanka. We observed 286 individually-identified adult female elephants over 20 months and examined their social dynamics at three levels of organization: pairs of individuals (dyads), small sets of direct companions (ego-networks), and the population level (complete networks).ResultsCorroborating previous studies of this and other Asian elephant populations, we find that the sizes of elephant groups observed in the field on any particular day are typically small and that rates of association are low. In contrast to earlier studies, our longitudinal observations reveal that individuals form larger social units that can be remarkably stable across years while associations among such units change across seasons. Association rates tend to peak in dry seasons as opposed to wet seasons, with some cyclicity at the level of dyads. In addition, we find that individuals vary substantially in their fidelity to companions. At the ego-network level, we find that despite these fluctuations, individuals associate with a pool of long-term companions. At the population level, social networks do not exhibit any clear seasonal structure or hierarchical stratification.ConclusionsThis detailed longitudinal study reveals different social dynamics at different levels of organization. Taken together, these results demonstrate that low association rates, seemingly small group sizes, and fission-fusion grouping behavior mask hidden stability in the extensive and fluid social affiliations in this population of Asian elephants.

Extraordinary elephant perception

“…The 4-kg elephant brain is remarkably complex, and in many ways, mirrors our own (14,15). Recent studies put elephant social complexity on a par with that of the great apes, including findings of their capacities for mirror self-recognition, cooperation, empathy, and problem-solving (16)(17)(18)(19)(20). It is then of little surprise that they are learning to adapt to their changing natural environments, but quite disturbing that we are forcing them to do so.…”

Disentangling social networks from spatiotemporal dynamics: the temporal structure of a dolphin society

“…Many studies use more restrictive observation thresholds to intentionally remove any transient individual and focus on the social organization of the core of residents (e.g. Wolf et al 2007;de Silva et al 2011;de Silva & Wittemyer 2012). Based on the population dynamics of our studied system (see Rossi-Santos et al 2007;Cantor et al 2012), we specifically considered transient individuals to explore the dynamics of an open social system and its influence on the interpretation of the social patterns (see Fig.…”

“…Lehmann & Boesch 2004). In fact, time dependence of social interactions (Hinde 1976;Whitehead 1995) can be caused by substantial changes in population composition, which would forestall interactions among temporally segregated individuals (Whitehead 1999;de Silva et al 2011). If a social network could embed such spatiotemporal dynamics in its structure, then social modules could emerge from the opportunities to interact, depicting individuals with similar habitat preferences or that composed the population during the same time.…”

African forest elephant social networks: fission-fusion dynamics, but fewer associations

“…Even when filtering associations and including only individuals spending >10% of their time together, large components still exist (5 to 13 adult females). In the Asian elephant population, despite observed smaller group sizes (2.8 to 3.0 adult females), population-level networks consisted of 5 to 10 components, plus solitary individuals (de Silva et al 2011), which was more disconnected than the savanna elephant population, but more connected than our global network of 27 components and 30 solitary individuals.The networks also vary in sampling and the number of times individuals were seen, which can impact structure and present a source for the differences detected. Savanna elephants were observed for 36 mo (recapture values not included); Asian elephants for 20 mo, with 9 as the mode recapture rate; and forest elephants for approximately 15 mo, with a low recapture rate (mode of 2).…”