Stress hormones, social associations and song learning in zebra finches

The use of information provided by others is a common short-cut adopted to inform decision20 making. However, instead of indiscriminately copying others, animals are often selective in what, when, and whom they copy. How do they decide which “social learning strategy” to use? Previous research indicates that stress hormone exposure in early life may be important: while juvenile zebra finches copied their parents’ behaviour when solving novel foraging tasks, those exposed to elevated levels of corticosterone during development copied only unrelated adults. Here we tested whether this switch in social learning strategy generalises to vocal learning. In zebra finches, juvenile males often copy their father’s song; would corticosterone-treated juveniles in free-flying aviaries switch to copying songs of other males? We found that corticosterone-treated juveniles copied their father’s song less accurately as compared to control juveniles. We hypothesised that this could be due to having weaker social foraging associations with their fathers, and found that sons that spent less time foraging with their fathers produced less similar songs. Our findings are in line with a novel hypothesis linking early-life stress and social learning: early-life corticosterone exposure may affect social learning indirectly as a result of the way it shapes social affiliations.