Résumé
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.