The number of strong social bonds is linked to survival in a cooperative bird

Gabriel Munar-Delgado , Matthieu Paquet, Babette Fourie, Franck Theron, André Ferreira, Claire Doutrelant, Rita Covas

Recent evidence, particularly from mammals, shows that variation in the quality of social relationships is associated with survival. In parallel, studies across diverse taxa have reported that social network traits can show consistent individual differences over time. However, few studies have assessed whether the specific social traits that predict survival are also repeatable within individuals, limiting our understanding of their contribution to fitness variation.  To address this, we used a long-term study of sociable weavers (Philetairus socius), a cooperative bird, to quantify individual sociality as the relative number of strong social bonds within colony-year foraging networks, capturing preferential associations. We then estimated its repeatability and association with seasonal survival using multi-state capture–recapture models that account for state-dependent detection. Individual sociality was moderately repeatable across years, indicating consistent differences among individuals despite temporal variation in social environments. Sociality was also positively associated with survival: more social individuals had higher survival probabilities than less social individuals in both winter and summer periods.  These findings suggest that sociality may contribute to fitness variation and be subject to selection in this system, adding to the growing evidence that the quality of social bonds has adaptive value across taxa.