Sociability increases survival of adult female giraffes

For female giraffes, company predicted survival better than their strongest relationships. Females regularly seen alongside more other females were more likely to survive, even though their groups kept changing. That distinction matters: spending time in company and maintaining a particularly close relationship are different ways of being social, and they need not have the same consequences.

Monica Bond, Derek Lee and colleagues followed adult female Masai giraffes in Tanzania's Tarangire ecosystem from 2012 to 2016. Photographs identified individuals by their coat patterns. For 512 females seen often enough to assess their associations, the team compared survival estimates with average numbers of female companions, relationship strength, vegetation and proximity to human settlements. Their models also accounted for differences in the chances of seeing an animal again.

Females with more female companions had higher estimated survival, with the increase flattening around three companions on average. The strength of their closest measured relationship did not explain survival in the same way. This observational link does not establish that company caused better survival, or identify how it might help. It does show that a changing group need not be socially unimportant: regular company can matter even without a fixed membership.