Are fission–fusion dynamics consistent among populations? A large‐scale study with Cape buffalo

Abstract

Fission–fusion dynamics allow animals to manage costs and benefits of group living by adjusting group size. The degree of intraspecific variation in fission–fusion dynamics across the geographical range is poorly known. During 2008–2016, 38 adult female Cape buffalo were equipped with GPS collars in three populations located in different protected areas (Gonarezhou National Park and Hwange National Park, Zimbabwe; Kruger National Park, South Africa) to investigate the patterns and environmental drivers of fission–fusion dynamics among populations. We estimated home range overlap and fission and fusion events between Cape buffalo dyads. We investigated the temporal dynamics of both events at daily and seasonal scales and examined the influence of habitat and distance to water on event location. Fission–fusion dynamics were generally consistent across populations: Fission and fusion periods lasted on average between less than one day and three days. However, we found seasonal differences in the underlying patterns of fission and fusion, which point out the likely influence of resource availability and distribution in time on group dynamics: During the wet season, Cape buffalo split and associated more frequently and were in the same or in a different subgroup for shorter periods. Cape buffalo subgroups were more likely to merge than to split in open areas located near water, but overall vegetation and distance to water were very poor predictors of where fission and fusion events occurred. This study is one of the first to quantify fission–fusion dynamics in a single species across several populations with a common methodology, thus robustly questioning the behavioral flexibility of fission–fusion dynamics among environments.

COMBINED USE OF REMOTE SENSING AND SPATIAL MODELLING: WHEN SURFACE WATER IMPACTS BUFFALO (SYNCERUS CAFFER CAFFER) MOVEMENTS IN SAVANNA ENVIRONMENTS

“…Given the few individuals used to calibrate buffalo herd behaviour, proven dynamics such as fission-fusion within buffalo herds (Wielgus et al, 2020) are not reproduced by the model. Despite this limitation, the model has been able to coherently simulate the movement of 200 buffalo individuals influencing each other's direction in relation with surface water availability (c.f.…”

Inter‐Group Social Behavior, Contact Patterns and Risk for Pathogen Transmission in Cape Buffalo Populations

“…In contrast, social species often form groups in which associations between individuals, and therefore the use of common space, vary depending on whether the group is stable over long time periods or subject to fission‐fusion dynamics (Aureli et al 2008). Irrespective of the factors mediating sociality, individuals within groups usually spend a significant amount of time together, which increases the potential for pathogen transmission within social groups (Altizer et al 2003, Wielgus et al 2020). At the landscape level, the spread of infectious diseases is also dependent on movements and interactions between social groups (Weber et al 2013, Vanderwaal et al 2016).…”

“…In contrast, adult males move regularly between mixed‐sex groups and smaller all‐male bachelor groups (2–30 individuals up to 50) according to seasonal mating opportunities, forage availability, and predation avoidance (Sinclair 1977, Prins 1996, Halley and Mari 2004, Hughes et al 2017). Mixed‐sex groups occupy identifiable and stable home ranges with fixed membership and size, and within these large groups, subgroups of individuals regularly split and merge according to seasonality, group size, and predation pressure (fission‐fusion dynamics; Sinclair 1977, Prins 1996, Ryan et al 2006, Tambling et al 2012, Wielgus et al 2020). The relatively recent availability of telemetry data has enabled the examination of within‐group contact patterns across several populations over long time periods (Wielgus et al 2020).…”

“…Mixed‐sex groups occupy identifiable and stable home ranges with fixed membership and size, and within these large groups, subgroups of individuals regularly split and merge according to seasonality, group size, and predation pressure (fission‐fusion dynamics; Sinclair 1977, Prins 1996, Ryan et al 2006, Tambling et al 2012, Wielgus et al 2020). The relatively recent availability of telemetry data has enabled the examination of within‐group contact patterns across several populations over long time periods (Wielgus et al 2020). Wielgus et al (2020) demonstrated that subgroups split and merge regularly for short periods (usually 1–3 days), with greater frequency during the wet season.…”

“…The relatively recent availability of telemetry data has enabled the examination of within‐group contact patterns across several populations over long time periods (Wielgus et al 2020). Wielgus et al (2020) demonstrated that subgroups split and merge regularly for short periods (usually 1–3 days), with greater frequency during the wet season. Fission‐fusion dynamics may indirectly promote the spread of pathogens at the landscape scale, but inter‐group contact patterns and their effect on the spread of pathogens remain poorly understood (but see Bennitt et al 2018 for a study on intergroup social behavior of Cape buffalo).…”