Sociability increases survival of adult female giraffes

Studies increasingly show that social connectedness plays a key role in
determining survival, in addition to natural and anthropogenic
environmental factors. Few studies, however, integrated social,
non-social, and demographic data to elucidate what components of an
animal’s socio-ecological environment are most important to their
survival. Female giraffes (Giraffa camelopardalis) form structured
societies with highly dynamic group membership but stable long-term
associations. We examined the relative contributions of sociability
(relationship strength, gregariousness, and betweenness), together with
those of the natural (food sources and vegetation types) and anthropogenic
environment (distance from human settlements), to adult female giraffe
survival. We tested predictions about the influence of sociability and
natural and human factors at two social levels: the individual and the
social community. Survival was primarily driven by individual- rather than
community-level social factors. Gregariousness (the number of other
females each individual was observed with on average) was most important
in explaining variation in female adult survival, more than other social
traits and any natural or anthropogenic environmental factors. For adult
female giraffes, grouping with more other females, even as group
membership frequently changes, is correlated with better survival, and
this sociability appears to be more important than several attributes of
their non-social environment.