Many species of birds of a certain longevity adopt different social strategies throughout their lives that imply gregariousness in the juvenile stage and territoriality , more "solitary", in adulthood. However, the potential costs associated with these strategies, such as stress, are poorly understood. Scientists from the CSIC's Doñana Biological Station have analyzed the effects of group living, sex and parasite load on the basal concentrations of stress hormones (corticosterone) in a wild population of crows ( Corvus corax ). The results suggest a fundamental role of social context in stress levels, as well as that living in a group can be more energetically demanding than maintaining a territory . Their findings are published in the journal Biology letters .
These results have implications for the understanding of hormonal mechanisms in different lifestyles and may inspire new research on the relationship between hormone levels and selective pressures in gregarious and territorial strategies in birds of certain longevity, as well as in other species.
